
Class J2*£52_ 
Book vS H> 



/ 



THE PRESENT STATUS 



OF 




MILITARY AERONAUTICS 



GEORGE O. SQUIER, Ph.] 



Major- Signal ( 



U. S. Ai 



Reprint from The Journal 

The American Society of Mechanical Engineers 






By transfer 
JAN 2I190S 



THE PRESENT STATUS OF MILITARY 
AERONAUTICS 

CONTENTS 

I NTRODUCTION . . 1 571 

I. AEROSTATION 

Successful Military Dirigible Balloons 1574 

France: The Patrle; La Republique, YiUe de Paris 1574 

England: Military Dirigible No 1 1582 

Germany: The Gross; the Parseval; the Zeppelin 1584 

United States: Dirigible Xo. 1 1589 

Balloon Plant at Fort Omaha, Xeb 1590 

Some General Consideration's which Govern the Design of a Dirig- 
ible Balloon 1591 

Buoyancy and Shape 1591 

Resistance of the Air to the Motion of a Projectile 1594 

Analogy to Airship 1594 

Aerodynamic Adjustments 1596 

a Static Balance 1596 

b Dynamic Balance 1596 

c Stability 1596 

d Natural Period and Oscillations 1597 

II. AVIATION 

REPRESEXTATVE AEROPLANES OF VARIOUS TYPES 

The Wright Brothers' Aeroplane 1597 

The Herring Aeroplane 1598 

The Farman Aeroplane 1598 

The Bleriot Aeroplane 1599 

The June Bug 1599 

Some General Considerations which Govern the Design of ajn Aero- 
plane 1600 

a Support 1 600 

Principle of Reefing in Aviation liiOl 

Determination of k for Arched Surfaces L602 

l> Resistance and Propulsion 1ih)l' 

Most Advantageous Speed and Angle of Flight 1603 

c Stability and Control 1605 



CONTENTS 
111. HYDROMECHANIC RELATIONS 

On Some General Relations Between Ships in Air and in Water L607 

Helmholtz's Theorem 1608 

Skin-Friction 1609 

Relative Dynamic and Buoyant Support 1010 

Motors 1611 

Propellers 101 1 

Limitations 1611 

IV. AERIAL LOCOMOTION IN WARFARE 

Hague Peace Conference 1612 

Influence on Military Art 1613 

Delimitation of Frontiers 1615 

Interior Harbors 1010 

Appendix 1 

United States Signal Corps Specification for Heavier-than-air Flying 

Machine 1018 

Appendix 2 
United States Signal Corps Specification for Dirigible Balloon 1021 

Appendix 3 
Bibliography 1024 



THE PRESENT STATUS OF MILITARY 
AERONAUTICS 

By Dr. George O. Squier 

MAJOR, SIGNAL CORPS, U. S. ARMY 

Non-Member 

It is a matter of first significance that The American Society of 
Mechanical Engineers, composed of a body of highly trained and 
serious minded men, should be considering in annual meeting assem- 
bled the subject of aerial navigation. Five years ago such a subject 
could scarcely have had a place on the list of professional papers 
on your program. The present period will ever be memorable in 
the history of the world for the first public demonstrations of the 
practicability of mechanical flight. In fact, at the present moment 
a resistless wave of enthusiasm and endeavor, sweeping away every 
prejudice, is passing over the entire civilized world, fixing the atten- 
tion of all classes upon the problem of flight. France, Germany, 
and England are in a state of frenzied interest in this subject, and 
each period of a single month sees some new step accomplished in the 
march of progress. The Universal Highway is at last to be made 
available for the uses of mankind, with its consequent influence upon 
our modes of life and thought. 

2 The subject of war balloons and their accessories pertains by 
law to the Signal Corps of the Army, and some months since an 
invitation was extended to the Chief Signal Officer of the Army, 
Gen. James Allen, to meet with you on this occasion and present to 
this distinguished body of practical engineers an outline of the work 
of the Government in this direction. On account of pressure 
of official duties General Allen has designated me to perform this 
duty, and notwithstanding a keen consciousness of personal short- 
comings, yet I would be indeed lacking in sentiment if I failed to 
acknowledge the honor felt in appearing here today to present such 



Presented at the New York Meeting (December 1908) of The American Society 
of Mechanical Engineers. All papers arc subject to revision 



1572 PRESENT STATUS OF MILITARY AERONAUTICS 

a subject for the first time before a national body of American 
engineers. 

3 At the outset, it must be stated that the subject is so vast in 
its scientific details and that data and results are being obtained so 
rapidly that it is manifestly impossible to present more than the 
merest outline of the present state of this new Science and Art 
within the limits of a short paper. From the earliest times men 
have dreamed of imitating the birds in sailing through the air, yet it 
is only within a very few years that the strength of materials and 
the mechanical construction of motors have reached a state to make 
power-flight possible. The industrial development of the automobile 
has been a powerful ally in the realization of mechanical flight, and 
the engineering profession finds itself equipped and ready to further 
the development of this great problem. 

4 On December 23, 1907, the Signal Corps of the Army issued a 
public advertisement and specification calling for bids for furnishing 
the Government with a heavier-than-air flying machine. A copy 
of this specification is appended to this paper as of possible historical 
interest. 

5 The conditions of this specification require that the Govern- 
ment be furnished with a heavier-than-air flying machine capable 
of carrying one passenger besides the aviator, and it must remain 
in the air on an endurance test for a period of one hour without land- 
ing, and must also be subjected to a speed test over a measured 
course of more than five miles, against and with the wind, attain- 
ing a minimum speed of 36 miles per hour. The machine must, in 
addition, carry fuel for a continuous flight of not less than 125 
miles. 

6 In preparing this specification, it was purposely sought to 
leave the bidder perfectly free in the methods to be employed, and 
he was not restricted as to type or design. At the time this specifi- 
cation was issued eleven months ago, the conditions were publicly 
regarded as being unusually severe and far beyond the state of the 
art at that time. That these conditions were justified has been 
subsequently proved, as is now well known. 

7 Although the public advertisement called for but one heavier- 
than-air machine, yet when the bids were opened it was found possible 
through the cooperation of the Board of Ordnance and Fortification, 
to award contracts to each bidder who complied with the require- 
ments of the law in every respect, and consequently contracts were 
ultimately awarded to the Wright Brothers of Dayton, Ohio, for the 



PRESENT STATUS OF MILITARY AERONAUTICS 1573 

sum of S25 000 for a 40-mile speed, and also to A. M. Herring of 
Xew York, for the sum of S20 000. 

8 It was believed that the acceptance by the Government of 
each of the bids submitted instead of but one of them would serve 
as an additional stimulus to develop practical aviation in the United 
States, and at the same time serve to supply the War Department 
with machines needed in military service. This dual object. — -to 
advance a new art of interest to the nation as a whole, and to secure 
necessary equipment for the military establishment. — has been in 
the past and is at present the policy of the Signal Corps of the Army. 

9 The result of issuing this specification, as well as a similar one 
for supplying a small dirigible balloon for the preliminary training 
of the men of the Signal Corps, was an awakening of interest in this 
subject throughout the country to such an extent that the Signal 
Office continues to receive daily a large number of letters, plans, 
and models proposing manifold schemes for navigating the air. 

10 The Aeronautical Division of the Office of the Chief Signal 
Officer of the Army was organized on July 1, 1907, and the Aeronau- 
tical Board of the Signal Corps was appointed in July of the current 
year for conducting tests of dirigible balloons and aeroplanes under 
existing contracts. 

11 It should be stated that the mention of particular types of 
dirigible balloons and aeroplanes in this paper must not be considered 
as an official indorsement of these particular machines, nor the failure 
to mention other types be construed to indicate a lack of equal 
recognition of the merits of the latter. In the case of the AYright 
Brothers, however, it is desired to associate the Signal Corps of the 
Army publicly and officially with the present universal recognition 
of their work in advancing the Science and Art of Aviation. These 
results have been due to the persistence, daring, and intelligence of 
these American gentlemen, to whom the whole world is now paying- 
homage. It will ever be recorded that the classic series of public 
demonstrations first -made by Orville AYright at the Government 
testing grounds at Fort Myer, Ya., in September, 1908, and by Wilbur 
AA "right at Le Mans. France, made a profound impression through- 
out the world, and kindled especially the patriotic spirit of the 
American people. 

12 There are two general classes of vehicles of the air, (a) those 
which depend for their support upon the buoyancy of some gas 
lighter than air, and (b) those which depend for such support upon 
the dynamic reaction of the air itself. These classes are designated 



1574 PRESENT STATUS OF MILITARY AERONAUTICS 

a Lighter-than-air types: 

Free balloons, dirigible balloons or airships 
b Heavier-than-air types: 

Aeroplanes, orthopters, helicopters, etc. 

13 It should be remarked, however, that these two general 
classes exhibit a growing tendency to overlap each other. For 
example, the latest dirigible balloons are partly operated by means 
of aeroplane surfaces, and are also often balanced so as to be slightly 
heavier than the air in which they move, employing the propeller 
thrust and rudder surfaces to control the altitude. 

I. AEROSTATION 

14 Captive and free balloons, with the necessary apparatus and 
devices for operating the same, have been for many years considered 
an essential part of the military establishment of every first-class 
Power. They played a conspicuous part in the siege of Paris, and 
were often valuable in our own Civil War. The construction and 
operation of aerostats are too well understood to need further atten- 
tion here. 

Successful Military Dirigible Balloons 

FRANCE 

15 Two types of dirigible balloons have been used in the French 
Army; first the Patrie, and second the Ville de Paris. 

16 The Patrie was developed by Julliot, an engineer employed by 
the Lebaudy Brothers at their sugar refinery in Paris. A history of 
his work beginning in 1896 is fully given in La Conquete de V Air. 

THE PATRIE 

17 The Patrie, the third of its type, was first operated in 1906. 
The gas bag of the first balloon was built by Surcouf at Billancourt, 
Paris. The mechanical part was built at the Lebaudy Sugar Refinery. 
Since then the gas bags have been built at the Lebaudy balloon shed 
at Moisson, near Paris, under the direction of their aeronaut, Juchmes. 
The gas bag of the Patrie was 197 ft. long with a maximum diameter of 
33 ft. 9 in., situated about 2/5 of the length from the front; volume 
111 250 cu. ft.; length approximately six diameters. This relation, 
together with the cigar shape, is in accordance with the plans of Colonel 



PRESENT STATUS OF MILITARY AERONAUTICS 1575 

Renard's dirigible, built and operated in France in 1884; the same 
general shape and proportions being found in the Ville de Paris. 

18 The first Lebaudy was pointed at the rear, which is generally 
admitted to be the proper shape for the least resistance, but to main- 
tain stability it was found necessary to put a horizontal and vertical 
plane there, so that it had to be made an ellipsoid of revolution to give 
attachment for these planes. 

19 The ballonet for air had a capacity of 22 958 cu. ft. or about i 
of the total volume. This is calculated to permit reaching a height of 
about one mile and to be able to return to the earth, keeping the gas 
bag always rigid. To descend from a height of one mile, gas would be 
released by the valve, then air pumped into the ballonet to keep the 
gas bag rigid, these two operations being carried on alternately. On 
reaching the ground from the height of one mile the air would be at the 
middle of the lower part of the gas bag and would not entirely fill 
the ballonet. To prevent the air from rolling from one end to the 
other when the airship pitches, thus producing instability, the ballonet 
was divided into three compartments by impermeable cloth parti- 
tions. Numerous small holes were pierced in these partitions through 
which the air finally reached the two end compartments. 

20 In September, 1907, the Patrie was enlarged by 17 660 cu. ft. 
by the addition of a cylindrical section at the maximum diameter, 
increasing the length but not the maximum diameter. 

21 The gas bag is cut in panels; the material is a rubber cloth made 
by the Continental Tire Company at Hanover, Germany. It con- 
sists of four layers arranged as follows : 

Weight oz. 
per square yard 

a Outer layer of cotton cloth covered with 

lead chromate 2.5 

b Layer of vulcanized rubber 2.5 

c Layer of cotton cloth 2.5 

d Inner layer of vulcanized rubber 2.21 

Total weight 9.71 

22 A strip of this cloth one foot wide tears at a tension of about 
934 lb. A pressure of about 1 in. of water can be maintained in the 
gas bag without danger. The lead chromate on the outside is to 
prevent the entrance of the actinic rays of the sun which would cause 
the rubber to deteriorate. The heavy layer of rubber is to prevent' the 



1576 PRESENT STATUS OF MILITARY AERONAUTICS 

leaking of the gas. The inner layer of rubber is merely to prevent 
deterioration of the cloth by impurities in the gas. This material 
has the warp of the two layers of cotton cloth running in the same 
direction and is called straight thread. The material in the ballonet 
weighs only about 7f oz. per sq. yd. and has a strength of about 
336 lb. per running foot. ^VUien the Patrie was enlarged in Septem- 
ber. 1907. the specifications for the material allowed a maximum 
weight of 10 oz. per sq. yd., a minimum strength of 907 lb. per running 
foot, and a loss of 5.1 cu. in. of hydrogen per square yard in twenty- 
four hours at a pressure of 1.18 in. of water. Bands of cloth are 
pasted over the seams inside and out with a solution of rubber to pre- 
vent leaking through the stitches. 

23 Suspension. One of the characteristics of the Patrie is the 
" short" suspension. The weight of the car is distributed over only 
about 70 ft. of the length of the gas bag. To do this, an elliptical 
shaped frame of nickel steel tubes is attached to the bottom of the gas 
bag; steel cables run from this down to the car. A small hemp net 
is attached to the gas bag by means of short wooden cross pieces or 
toggles which are let into holes in a strong canvas band which is 
sewed directly on the gas bag. The metal frame, or platform, is 
attached to this net by means of toggles, so that it can be quickly 
removed in dismounting the airship for transportation. The frame can 
also be taken apart. 28 steel cables about 0.2 in. in diameter run 
from the frame down to the car, and are arranged in triangles. Due 
to the impossibility of deforming a triangle, rigidity is maintained 
between the car and gas bag. 

24 The objection to the "short" suspension of the Patrie is the 
deformation of the gas bag. A distinct curve can be seen in the 
middle. 

25 The Car. The car is made of nickel steel tubes (12 per cent 
nickel). This metal gives the greatest strength for minimum weight. 
The car is boat-shaped, about 16 ft. long, about 5 ft. wide, and 2h ft. 
high. About 11 ft. separate the car from the gasbag. To prevent 
any chance of the fire from the engine communicating with the hydro- 
gen, the steel framework under the gas bag is covered with anon- com- 
bustible material. 

26 The pilot stands at the front of the car, the engine is in the 
middle, the engineer at the rear. Provision is made for mounting a 
telephotographic apparatus, and for a 100-candle-power acetylene 
search-light. A strong pyramidal structure of steel is built under the 
car, pointing downward. In landing the point comes to the ground 



PRESENT STATUS OF MILITARY AERONAUTICS 1577 

first and this protects the ear, and especially the propellers, from being 
damaged. The car is covered to reduce air resistance. It is so 
low, however, that part of the equipment and most of the bodies of 
those inside are exposed, so that the total resistance of the car is 
large. 

27 The Motor. The first Lebaudy had a 40 h. p. Daimler-Merce- 
des benzine motor. The Patrie was driven by a 60 to 70 h.p., 4-cylin- 
der Panhard and Levassor benzine motor, making 1000 r.p.m. 

28 The Propellers. There are two steel propellers 8^ ft. in 
diameter (two blades each) placed at each side of the engine, thus 
giving the shortest and most economical transmission. To avoid any 
tendency to twist the car, the propellers turn in opposite directions. 
They are "high speed," making 1000 to 1200 r.p.m. 

29 The gasolene tank is placed under the car inside the pyramidal 
frame. The gasoline is forced up to the motor by air compression. 
The exhaust is under the rear of the car pointing down and is covered 
with a metal gauze to prevent flames coming out. The fan which 
drives the air into the ballonet is run by the motor, but a dynamo is 
also provided so that the fan can always be kept running even if the 
motor stops. This is very essential as the pressure must be main- 
tained inside the gas bag so that the latter will remain rigid and keep 
its form. There are five valves in all, part automatic and part both 
automatic and also controlled from the car with cords. The valves in 
the ballonet open automatically at less pressure than the gas valves, 
so that when the gas expands all the air is driven out of the ballonet 
before there is any loss of gas. The ballonet valves open at a pres- 
sure of about 0.78 in. of water, the gas valves at about 2 in. 

30 Stability. Vertical stability is maintained by means of fixed 
horizontal planes. One having a surface of 150 sq. ft. is attached at 
the rear of the gas bag, and due to its distance from the center of 
gravity is very efficient. The elliptical frame attached under the gas 
bag has an area of 1 055 sq. ft. but due to its proximity to the center 
of gravity, has little effect on the stability. Just behind the ellip- 
tical frame is an arrangement similar to the feathering on an arrow. 
It consists of a horizontal plane of 150 sq. ft., and a vertical plane of 
113 sq. ft. To maintain horizontal stability, that is, to enable the 
airship to move forward in a straight line without veering to the sides, 
fixed vertical planes are used. One runs from the center to the rear 
of the elliptical frame and has an area of 108 sq. ft. 

31 In'addition to the vertical surface of 113 sq. ft. at the rear of 
the elliptical frame, there is a fixed plane of 150 sq. ft. at the rear of 



L578 PRESENT STATUS OF MILITARY AERONAUTICS 

the gas bag. To fasten the two perpendicular planes at the rear of 
the gas bag, cloth flaps are sewed directly on the gas bag. Nickel 
steel tubes are placed in the flaps which are then laced over the tubes. 
With these tubes as a base, a light tube and wire framework is 
attached and water-proof cloth laced on this framework. Addi- 
tional braces run from one surface to the other and from each sur- 
face to the gas bag. The rudder is at the rear under the gas bag. It 
has about 150 sq. ft. and is balanced. 

32 A movable horizontal plane near the center of gravity, above 
the car, is used to produce rising or descending motion, or to prevent 
an involuntary rising or falling of the airship due to expansion or con- 
traction of the gas or to other causes. After the adoption of this 
movable horizontal plane, the loss of gas and ballast was reduced to a 
minimum. Ballast is carried in 10 and 20 lb. sand bags. A pipe 
runs through the bottom of the car from which the ballast is thrown. 

33 There are two long guide ropes, one attached at the -front of the 
elliptical frame and the other on the car. On landing, the one in 
front is seized first so as to hold the airship with the head to the wind. 
The motor may then be stopped and the descent made by pulling 
down on both guide ropes. A heavy rope, 22 ft. long, weighing 110 
lb. is attached on the end of a 164 ft. guide rope. This can be dropped 
out on landing to prevent coming to the ground too rapidly. The 
equipment of the car includes a " siren," speaking trumpet, carrier 
pigeons, iron pins and a rope for anchoring the airship, reserve supply 
of fuel and water, and fire extinguisher. 

34 After being enlarged in September, 1907, the Patrie made a 
number of long trips at an altitude of 2 500 to 3 000 ft. In November 
1907, she went from Paris to Verdun, near the German frontier, a 
distance of about 175 miles, in about 7 hours, carrying four persons. 
This trip was made in a light wind blowing from the northeast. Her 
course was east, so that the wind was unfavorable. On Friday, 
November 29, 1907, during a flight near Verdun, the motor stopped 
due to difficulty with the carburetter. The airship drifted with the 
wind to a village about 10 miles away where she was safely landed. 
The carburetter was repaired on the 30th. Soon after, a strong wind 
came up and tore loose some of the iron pickets with which it was 
anchored. This allowed the airship to swing broadside to the wind; 
it then tilted over on the side far enough to let some of the ballast bags 
fall out. The 150 or 200 soldiers who were holding the ropes were 
pulled along the ground until directed by the officer in charge to let go. 
After being released, it rose and was carried by the wind across the 



PRESENT STATUS OF MILITARY AERONAUTICS 1579 

north of France, the English Channel, and into the north of Ireland. 
It struck the earth there, breaking off one of the propellers and then 
drifted out to sea. 

THE REPUBLIQUE 

35 This is the latest of the French military dirigible balloons, and 
differs but slightly from its predecessor, the Patrie. The volume has 
been increased by about 2 000 cu. ft. The length has been reduced 
to 200 ft. and the maximum diameter increased to 35J ft. The 
shape of the gas bag accounts for the 2 000 additional cubic feet of 
volume. The motor and propellers are as in the Patrie. The total 
lifting capacity is 9 000 lb., of which 2 700 lb. are available for passen- 
gers, fuel, ballast, instruments, etc. Its best performance was a 
125-mile flight made in 6J hours against an unfavorable wind. 

36 The material for the gas bag of the new airship was furnished 
by the Continental Tire Company. It is made up as follows: 

Weight oz. 
per square yard 

Outer yellow cotton layer 3 . 25 

Layer of vulcanized rubber 3 . 25 

Layer of cotton cloth 3 . 25 

Inner layer of rubber . 73 

Total weight 10.48 

37 It is interesting to note the changes which this type has under- 
gone since the first one was built. The Jaime, constructed in 1902-03; 
was pointed at the rear and had no stability plane there; later it was 
rounded off at the rear and a fixed horizontal plane attached. Finally 
a fixed vertical plane was added. The gas bag has been increased in 
capacity from 80 670 cu. ft. to about 131 000 cu. ft. The manufac- 
turers have been able to increase the strength of the material of which 
the gas bag is made, without materially increasing the weight. The 
rudder has been altered somewhat in form. It was first pivoted on 
its front edge, but later on a vertical axis, somewhat to the rear of this 
edge. With the increase in size, has come an increase in carrying 
capacity and consequently a greater speed and more widely extended 
field of action. 

VILLE DE PARIS 

38 This airship was constructed for Mr. Deutsch de la Meurthe, of 
Paris, who has done a great deal to encourage aerial navigation. The 



1580 PRESENT STATUS OF MILITARY AERONAUTICS 

si ViUe de Paris was built in 1902, on plans drawn by Tatin, a 
French aeronautical engineer. It was not a success. Its successor 
was built in 1900. on plans of Surcouf, an aeronautical engineer 
and balloon builder. The gas bag was built at his works in Billan- 
couit. the mechanical part at the Voisin shop, also in Billancourt. 
The plans are based on those of Colonel Renard's airship, the France, 
built in 1SS4, and the Vitte de Paris resembles the older airship in 
many particulars. In September, 1907, Mr. Deutsch offered the use 
of his airship to the French Government. The offer was accepted, 
but delivery was not to be made except in case of war or emergency. 
When the Patrie was lost in November, 1907, the military authorities 
immediately took over the Deutsch airship. 

39 Gas Bag. The gas bag is 200 ft. long for a maximum diameter 
of 34-i- ft., giving a length of about 6 diameters, as in the France 
and the Patrie. Volume 112 847 cu. ft. maximum diameter at 
about | of the distance from the front, approximately, as in the Patrie. 
The middle section is cylindrical with conical sections in front and 
rear. At the extreme rear is a cylindrical section with eight smaller 
cylinders attached to it. The ballonet has a volume of 21 192 cu. 
ft., or about A of the whole volume, the same proportion found in 
the Patrie. The ballonet is divided into three compartments from 
front to rear. The division walls are of permeable cloth, and are not 
fastened to the bottom so that when the middle compartment fills 
with air, and the ballonet rises, the division walls are lifted up from 
the bottom of the gas bag, and there is free communication between 
the three compartments. The gas bagis made up of a series of strips 
perpendicular to a meridian line. These strips run around the bag, 
their ends meeting on the under meridian. This is known as the 
"brachistode" method of cutting out the material, and has the 
advantage of bringing the seams parallel to the line of greatest ten- 
sion. They are therefore more likely to remain tight and not allow 
the escape of gas. The disadvantage lies in the fact that there is a 
loss of 33 J per cent of material in cutting. The material was fur- 
nished by the Continental Tire Company, and has approximately the 
same tensile strength and weight as that used in the Patrie. It 
differs from the other in one important feature — it is diagonal-thread, 
that is, the warp of the outer layer of cotton cloth makes an angle of 
45 deg. with the warp of the inner layer of cotton cloth. The result 
is to localize a rip or tear in the material. A tear in the straight 
thread material will continue along the warp, or the weave, until it 
reaches a seam. 



PRESENT STATUS OF MILITARY AERONAUTICS 1581 

40 Valves. There are five in all, made of steel, about fourteen 
inches in diameter; one on the top connected to the car by a cord, oper- 
ated by hand only; two near the rear underneath. These are auto- 
matic but can be operated by hand from the car. Two ballonet 
valves directly under the middle are automatic and are also operated 
from the car by hand. The ballonet valves open automatically at a 
pressure of § in. of water, the gas valves open at a higher pressure. 

41 Suspension. This airship has the "long" suspension. That 
is, the weight is distributed along practically the entire length of the 
gas bag. A doubled band of heavy canvas is sewn with six rows of 
stitches along the side of the gas bag. Hemp ropes running into steel 
cables transmit most of the weight of the car to these two canvas 
bands and thus to the gas bag. On both sides and below these first 
bands are two more. Lines run from these to points half way between 
the gas bag and the car, then radiate from these points to different 
points of attachment on the car. This gives the triangular or non- 
deformable system of suspension, which is necessary in order to have 
the car and gas bag rigidly attached to each other. With this " long" 
suspension, the Ville de Paris does not have the deformation so notice- 
able in the gas bag of the Patrie. 

42 The Car. This is in the form of a trestle. It is built of wood 
with aluminum joints and 0.12 in. wire tension members. It is 115 
ft. long, nearly 7 ft. high at the middle, and a little over 5 J ft. wide 
at the middle. It weighs 660 lb. and is considered unnecessarily 
large and heavy The engine and engineer are well to the front, the 
aeronaut with steering wheels is about at the center of gravity. 

43 Motor. The motor is a 70 to 75 h.p. "Argus," and is excep- 
tionally heavy. 

44 Propeller. The propeller is placed at the front end of the car. 
It thus has the advantage of working in undisturbed air; the disad- 
vantage is the long transmission and difficulty in attaching the pro- 
peller rigidly. It has two blades and is 19.68 ft. long with a pitch of 
26.24 ft. The blades are of cedar with a steel arm. The propeller 
makes a maximum of 250 turns per minute when the engine is making 
900 rev. Its great diameter and width compensate for its small 
speed. 

45 Stability. This is maintained entirely by the cylinders at the 
rear. .Counting the larger one to which the smaller ones are attached, 
there are five, arranged side by side corresponding to the horizontal 
planes of the Patrie, and five vertical ones corresponding to the Patrie 1 s 
vertical planes. The volume of the small cylinders is so calculated 



1582 PRESENT STATUS OF MILITARY AERONAUTICS 

that the gas in them is just sufficient to lift their weight, so the}- neither 
increase or decrease the ascensional force of the whole. The horizon- 
tal projection of these cylinders is 1076 sq. ft. The center of this 
projection is 72 ft. from the center of gravity of the gas. The great 
objection to this method of obtaining stability, is the air resistance 
due to these cylinders, and consequent loss of speed. The stability of 
the Yillc de Paris in a vertical plane is said to be superior to that of the 
Patrie, due to the fact that the stability planes of the latter do not 
always remain rigid. The independent velocity of the Ville de 
Paris probably never exceeded 25 miles an hour. 

46 The Rudder. The rudder has a double surface of 150 sq. ft. 
placed at the rear end of the car, 72 ft. from the center uf gravity. It 
is not balanced, but is inclined slightly to the rear so that its weight 
would make it point directly to the rear if the steering gear should 
break. Two pairs of movable horizontal planes, one at the rear of the 
car having 43 sq. ft., and one at the center of gravity (as on the Patrie) 
having 86 sq. ft. serve to drive the airship up or down without losing 
gas or ballast. 

47 Guide Ropes. A 400 ft. guide rope is attached at the front end 
of the car. A 230 ft. guide rope is attached to the car at the center of 
gravity. 

48 About thirty men are required to maneuver the Ville de Paris 
on the ground. The pilot has three steering wheels, one for the 
rudder and two for the movable horizontal planes. The instru- 
ments used are an aneroid barometer, a registering barometer giving 
heights up to 1600 ft. and an ordinary dynamometer which can be 
connected either with the gas bag or ballonet by turning a valve. A 
double column of water is also connected to the tube to act as a check 
on the dynamometer. Due to the vibration of the car caused by the 
motor, these instruments are suspended by rubber attachments. 
Even with this arrangement, it is necessary to steady the aneroid 
barometer with the hand in order to read it. The vibration prevents 
the use of the statoscope. 

ENGLAND 

MILITARY DIRIGIBLE XO. 1 

49 The gas bag of this airship was built about five years ago by 
Colonel Templar, formerly in command of the aeronautical establish- 
ment at Aldershot. His successor, Colonel Capper built the mechanical 
part during the spring and summer of 1907, with the assistance of Mr. 



PRESENT STATUS OF MILITARY AERONAUTICS 1583 

S. F. Cody, a mechanical engineer. It was operated by Colonel Capper 
as pilot, with Mr. Cody in charge of the engine. Several ascents were 
made at Aldershot. In October 1907, they made a trip from Alder- 
shot to London, a distance of about 40 miles, landing at the Crystal 
Palace. For several days the rain and wind prevented attempting 
the return journey. On October 10 a strong wind threatened to 
carry away the airship, so the gas bag was cut open by the sergeant 
in charge. 

50 Gas Bag. This is made of eight layers of gold beater's skin. 
It is cylindrical in shape with spherical ends. Volume S4 76S cu. ft.; 
length 111^ ft.: maximum diameter, 31^- ft. The elongation there- 
fore is only about 3f . There is no ballonet, but due to the toughness 
of the gold beater's skin, a much higher pressure can safely be main- 
tained than in gas bags of rubber cloth. Without a ballonet, how- 
ever, it would not be safe to rise to the heights reached by the Patrie. 

51 Valves. The valves are made of aluminum and are about 12 
in. in diameter. 

52 Suspension. In this airship they have succeeded in obtaining 
a ''long'' suspension with a short boat-shaped car, a combination 
very much to be desired, as it distributes the weight over the entire 
length of the gas bag and gives the best form of car for purposes of 
observation and for maneuvering on the ground. To obtain this 
combination they have had to construct a very heavy steel frame- 
work which cuts down materially the carrying capacity, and 
moreover, this framework adds greatly to the air resistance. This 
is the only airship in Europe having a net work to support the car. 
In addition, four silk bands are passed over the gas bag and wires 
run from their extremities clown to the steel frame. This steel 
frame is in two tiers; the upper is rectangular in cross-section and sup- 
ports the rudder and planes; the lower part is triangular in cross-sec- 
tion and supports the car. The joints are aluminum. 

53 The Car. This is of steel and is about thirty feet long. To 
reduce air resistance, the car is covered with cloth. 

54 Motor. A 40 to 50 h.p. S-cylinder Antoinette motor is used. 
It is set up on top of the car. The benzine tanks are supported above 
in the framework. Gravity feed is used. 

bb Propellers. There are two propellers, one on each side, with 
two blades each, as in the Patrie. They are made of aluminum, 10 ft. 
in diameter, and make 700 r.p.m. The transmission is by belt. 

56 Stability. This is maintained by means of planes. At the ex- 
treme rear is a large fixed horizontal plane. In front of this is a pair of 



1584 PRESENT STATUS OF MILITARY AERONAUTICS 

hinged horizontal planes. Under this is the hexagonal shaped rudder- 
It is balanced. Two pairs of movable horizontal planes, 8 ft. by 4 ft.> 
each placed a1Mhe front serve to guide the airship up and down* 
as in the Patric and Ville de Paris. These planes have additional 
inclined surfaces which are intended to increase the stability in a 
vertical plane. All these planes, both fixed and movable, are con- 
structed like kites, of silk stretched on bamboo frames. The guide 
rope is 150 ft. long. Speed attained, about 16 miles per hour. 
This airship with a few improvements added has been in operation the 
past few months. The steel framework connecting the gas bag to the 
car, is now entirely covered with canvas, which must reduce the resist- 
ance of the air very materially. The canvas covering, enclosing the 
entire bag, serves as a reinforcement to the latter and at the same 
time gives attachment to the suspension underneath. It is reported 
that a speed of 20 miles an hour has been attained with the recon- 
structed airship. 

57 A pyramidal construction similar to that on the Patrie has 
been built under the center of the car to protect the car and propellers 
on landing. A single movable horizontal plane placed at the front 
end of the car and operated by the pilot, controls the vertical mo- 
tion. 

GERMANY 

58 Three different types of airships are being developed in Ger- 
many. The Gross is the design of Major Von Gross, who commands 
the Balloon Battalion at Tegel near Berlin. The Parseval is being 
developed by Major Von Parseval, a retired German Officer, and the 
Zeppelin is the design of Count Zeppelin, also a retired officer of the 
German Army. 

THE GROSS 

59 The first airship of this type made its first ascension on July 
23, 1907. The mechanical part was built at Siemen's Electrical 
Works in Berlin; the gas bag^by the Riedinger firm in Augsburg. 

60 Gas Bag. The gas bag is made of rubber cloth furnished by 
the Continental Tire Company similar to that used in the Ville de 
Paris. It is diagonal-thread, but there is no inner layer of rubber, 
as they do not fear damage from impurities in the hydrogen gas. 
Length, 131^ ft.; maximum diameter, about 39J ft.; volume 63 576 
cu. ft. ; the elongation is about 3 J. The form is cylindrical with spher- 
ical cones at the ends, the whole being symmetrical. 



PRESENT STATUS OF MILITARY AERONAUTICS 1585 

61 Suspension. The suspension is practically the same as that 
of the Patrie. A steel and aluminum frame is attached to the lower 
part of the gas bag, and the car is suspended on this by steel cables. 
The objection to this system is even more apparent in the Gross than 
in the Patrie. A marked dip along the upper meridian of the gas 
bag shows plainly the deformation. 

62 The Car. The car is boat-shaped like that of the Patrie. It is 
suspended thirteen feet below the gas bag. 

63 Motor. The motor is a 20 to 24 h.p. ; 4-cylinder "Daimler- 
Mercedes." 

64 Propellers. There are two propellers 8 T 2 -g- ft. in diameter, 
each having two blades. They are placed one on each side, but well 
up under the gas bag near the center of resistance. The transmission 
is by belt. The propellers make 800 r.p.m. 

65 Stability. ' The same system, with planes, is used in the Von 
Gross as in the Patrie, but it is not nearly so well developed. At the 
rear of the rigid frame attached to the gas bag, are two fixed horizon- 
tal planes, one on each side. A fixed vertical plane runs down from 
between these horizontal planes, and is terminated at the rear by the 
rudder. A fixed horizontal plane is attached on the rear of the gas 
bag as in the Patrie. The method of attachment is the same, but the 
plane is put on before inflation in the Gross airship, afterwards in 
the Patrie. The stability of the Gross airship in a vertical plane is 
reported to be very good, but it is said to veer considerably in 
attempting to steer a straight course. 

66 The many points of resemblance between this dirigible and 
the Lebaudy type are worthy of notice. The suspension or means of 
maintaining stability, and the disposition for driving are in general 
the same. As first built, the Gi^oss had a volume of 14 128 cu. ft. less 
than at present, and there was no horizontal plane at the rear of the 
gas bag. Its maximum speed is probably fifteen miles per hour. As 
a result of his experiments of 1907, Major Von Gross has this year 
produced a perfected airship built on the same lines as his first, 
but with greatly increased volume and dimensions. The latest 
one has a volume of 176 000 cu. ft., is driven by two 75 h.p. Daimler 
motors, and has a speed of 27 miles per hour. 

67 On September 1 1 of this year, the Gross airship left Berlin at 
10.25 p.m., carrying four passengers, and returned the next day at 
11.30 a.m., having covered 176 miles in the period of a little over 13 
hours. This is the longest trip, both in point of time and distance 
ever made by any airship returning to the starting point. 



1586 PRESENT STATUS OF MILITARY AERONAUTICS 



THE PARSEVAL 

OS The Parseval airship is owned and controlled by the Society for 
the Study of Motor Balloons. This organization, composed of capi- 
talists, was formed practically at the command of the Emperor who 
is very much interested in aerial navigation. The Society has a cap- 
ital of 1 000 000 marks, owns the Parseval patents and is ready to con- 
struct airships of the Von Parseval type. The present airship was 
constructed by the Riedinger firm at Augsburg, and is operated from 
the balloon house of this Society at Tegel, ad j oining the military balloon 
house. 

69 The gas bag is similar in construction to that of the " Drachen" 
balloon, used by the army for captive work. Volume, 1 13 000 cu. ft., 
length 190 ft., maximum diameter 30^ ft. It is cylindrical in shape, 
rounded at the front end and pointed at the rear. The material was 
furnished by the Continental Tire Company. It is diagonal-thread, 
weighing about ll T 2 -jj oz. per sq. yd. and having a strength of about 
940 lb. per running foot. Its inner surface is covered with a layer of 
rubber. 

70 Ballonets. There are two ballonets, one at each end, each 
having a capacity of 10 596 cu. ft. The material in the ballonet 
weighs about 8 J oz. per sq. yd., the cotton layers being lighter than 
in the material for the gas bag. Air is pumped into the rear ballonet 
before leaving the ground, so that the airship operates with the front 
end inclined upward. The air striking underneath, exerts an upward 
pressure, as on an aeroplane, and thus adds to its lifting capacity. 
Air is pumped into the ballonets from a fan operated by the motor. 
A complex valve just under the middle of the gas bag, enables the 
engineer to drive air into either, or both ballonets. The valves also 
act automatically and release air from the ballonets at a pressure of 
about 0.9 in. of water. 

7 1 In the middle of the top of the gas bag, is a valve for releas- 
the gas. It can be operated from the car, and opens automatically 
at a pressure of about 2 in. of water. Near the two ends and on 
opposite sides, are two rip strips controlled from the car by cords. 

72 Suspension. The suspension is one of the characteristics of the 
airship, and is protected by patents. The car has four trolleys, two 
on each side, which run on two steel cables. The car can run back- 
wards and forwards on these cables, thus changing its position with 
relation to the gas bag. This is called " loose" suspension. Its 
object is to allow the car to take up, automatically, variations in 



PRESENT STATUS OF MILITARY AERONAUTICS 1587 

thrust due to the motor, and variations in resistance due to the air. 
Ramifications of hemp rope from these steel cables are sewn onto a 
canvas strip which in turn is sewn onto the gas bag. This part of the 
suspension is the same as in the Drachen balloon. The weight is dis- 
tributed over the entire length of the gas bag. 

73 The Car. The car is 16.4 ft. long and is built of steel tubes and 
wire. It is large enough to hold the motor and three men, though 
four or five may be taken. 

74 Motor. The motor is a 110 h.p. Daimler-Mercedes. Suf- 
ficient gasolene is carried for a run of 12 hours. 

75 Propeller. The propeller, like the suspension, is peculiar to 
this airship and is protected by patents. It has four cloth blades 
which hang limp when not turning. When the motor is running, 
these blades, which are carefully weighted with lead at certain 
points, assume the proper position due to the various forces acting. 
The diameter is 13f ft. The propeller is placed above the rear of 
the car near the center of resistance. Shaft transmission is used. 
The propeller makes 500 r.p.m. to 1000 of the motor. There is a space 
of 6-| ft. from the propeller blades to the gas bag, the bottom of the car 
being about 30 ft. from the gas bag. This propeller has the advan- 
tage of being very light. Its position, so far from the engine, neces- 
sarily incurs a great loss of power in transmission. 

76 The steering wheel at the front of the car, has a spring device 
for locking"] t in any position. 

77 The^lOOS model of this airship was constructed for the purpose 
of selling it to the Government. Among other requirements is a 12 
hour flight without landing, and a sufficient speed to maneuver against 
a 22-mile wind. A third and larger airship of this type is now under 
construction. 

THE ZEPPELIN 

78 The Zeppelin airship, of which there have been four, differs 
from all others in that the envelope is rigid. Sixteen separate gas 
bags are contained in an aluminum alloy framework having 16 sides, 
covered with a cotton and rubber fabric. The pressure of the air is 
taken up by this framework instead of by the gas bags. The gas bags 
are not entirely filled, thus leaving room for expansion. 

79 The rigid' frame is 446 ft. long, 424- ft. in diameter, and has 
ogival-shaped ends. It is braced about every 45 ft. by a number of 
rods crossing near the center, giving a cross section resembling a 
bicycle wheel. Vertical braces are placed at intervals the entire 



1588 PRESENT STATUS OF MILITARY AERONAUTICS 

length of the frame. The 16 gas bags are completely separated from 
each other by partitions of sheet aluminum. Under the framework is 
a triangular truss running nearly the entire length, the sides of the 
triangle being about S ft. The total volume of the gas bags is 460 000 
cu. ft. which gives a gross lift of about 32 000 lb. 

SO Suspension. The two cars are rigidly attached directly to 
the frame of the envelope, and a very short distance below it. 

81 Cars. The two cars are built like boats. The}^ are about 20 
ft. long, 6 ft. wide, 3 J ft. high; are placed about 100 ft. from each end 
and are made of the same aluminum alloy. To land the airship, it is 
lowered until the cars float on the water, when it can be towed like a 
ship. A third car is built into the keel directly under the center of the 
framework, and is for passengers only. 

82 Motors. The power is furnished by two 110 h.p. Daimler- 
Mercedes motors, one placed on each car. Each weighs about 550 
lb. ; sufficient fuel for a 60 hours run can be carried. 

83 Propellers. A pair of three-bladed metal propellers about 15 
ft. in diameter is placed opposite each car, firmly attached to the 
frame of the envelope at the height of the center of resistance where 
they are most efficient. 

84 Stability. In addition to the long Y-shaped keel under the 
rigid frame, on each side at the rear of the frame are two nearly 
horizontal planes, while above and below the rear end are vertical 
fins. 

85 Steering. A large vertical rudder is attached at the extreme 
end of the rigid frame, and an additional one is placed between each 
set of horizontal planes on the sides. For vertical steering, there are 
four sets of movable horizontal planes placed near the ends of the 
rigid frame, about the height of the propellers. Each set consists of 
four horizontal planes placed one above the other and connected with 
rods, so that they work on the principle of a shutter. These horizon- 
tal rudders serve another very important purpose, due to the reac- 
tion of the air. When these planes are set at an angle of 15 deg. and 
the airship is making a> speed of 35 miles per hour, an upward pressure 
of over 1700 lb. is exerted, and consequently all the gas in one compart- 
ment could escape and yet by the manipulation of these planes, the 
airship could return safely to its starting point. 

86 Its best performances were two long trips made during the 
past summer. The first, July 4th, lasted exactly twelve hours, during 
which time it covered a distance of 235 miles, crossing the mountains 
to Lucerne and Zurich, and returning to the balloon house at Fried- 



PRESENT STATUS OF MILITARY AERONAUTICS 1589 

richshafen on Lake Constance. The average speed on this trip was 
32 miles per hour. On August 4 this airship attempted a 24-hour 
flight, which was one of the requirements made for its acceptance by 
the Government. It left Friedrichshafen in the morning with the 
intention of following the Rhine as far Mainz, and then returning to 
its starting point straight across the country. A stop of 4 hours and 
30 minutes was made in the afternoon of the first day on the Rhine, to 
repair the engine. On the return, a second stop was found necessary 
near Stuttgart, due to difficulties with the motors and the loss of gas. 
While anchored to the ground a storm came up, and broke loose the 
anchorages; and as the balloon rose in the air it exploded and took 
fire, due to causes which have never been actually determined and 
published, and fell to the ground, resulting in its complete destruction. 
On this journey, which lasted in all 31 hours and 15 minutes, the 
airship was in the air 20 hours and 45 minutes, and covered a total 
distance of 378 miles. 

87 The patriotism of the German nation was aroused. Subscrip- 
tions were immediately opened and in a short space of time $1 000 000 
had been raised. A Zeppelin Society was formed to direct the expend- 
iture of this fund. $85 000 has been expended for land near Fried- 
richshafen; shops are being constructed and it has been announced 
that within one year, the construction of 8 airships of the Zeppelin 
type will be completed. Recently the Crown Prince of Germany made 
atrip in the Zeppelin No. 3, which had been called back into service, 
and within a very few days the Emperor of Germany visited 
Friedrichshafen for the purpose of seeing the airship in flight. He 
decorated Count Zeppelin with the Order of the Black Eagle. Ger- 
man patriotism and enthusiasm has gone further, and the " German 
Association for an Aerial Fleet" has been organized in sections through- 
out the country. It announces its intention of building fifty garages 
(hangars) for housing airships. 

UNITED STATES 
SIGNAL CORPS DIRIGIBLE NO. 1 

88 Due to lack of funds, the United States Government has not 
been able to undertake the construction of an airship sufficiently 
large and powerful to compete with those of European nations. 
However, specifications were sent out last January for an airship not 
over 120 ft. long and capable of making 20 miles per hour. Contract 



1590 PRESENT STATUS OF MILITARY AERONAUTICS 

was awarded to Capt. Thomas S. Baldwin, who delivered an airship 
last August to the Signal Corps, the description of which follows: 

89 Gas Bag. The gas bag is spindle shaped, 96 ft. long, maxi- 
mum diameter 19 ft. 6 in. with a volume of 20 000 cu. ft. A ballonet 
for air is provided inside the gas bag, and has a volume of 2 S00 cu. ft. 
The material for the gas bag is made of two layers of Japanese silk, 
with a layer of vulcanized rubber between. 

90 Car. The car is made of spruce, and is 66 ft. long, 2\ ft. 
wide, and 2 J ft. high. 

91 Motor. The motor is a 20 h.p. water-cooled Curtiss make. 

92 Propeller. The propeller is at the front end of the car, and is 
connected to the engine by a steel shaft. It is built up of spruce, 
has a diameter of 10 ft. 8 in. with a pitch of 11 ft., and turns at the rate 
of 450 r.p.m. A fixed vertical surface is provided at the rear end of 
the car to minimize veering, and a horizontal surface attached to 
the vertical rudder at the rear tends to minimize pitching. . A double 
horizontal surface controlled by a lever and attached to the car in 
front of the engine, serves to control the vertical motion and also to 
minimize pitching. 

93 The position of the car very near to the gas bag, is one of the 
features of the Government dirigible. This reduces the length and 
consequently the resistance of the suspension, and places the pro- 
peller thrust near the center of resistance. 

94 The total lifting power of this airship is 1350 lb. of which 500 
lb. are available for passengers, ballast, fuel, etc. At its official 
trials a speed of 19.61 miles per hour was attained over a measured 
course ,and an endurance run lasting 2 hours, during which 70 per 
cent of the maximum speed was maintained. 

95 Dirigible A T o. 1. as this airship has been named, has already 
served a very important purporse in initiating officers of the Signal 
Corps in the construction and operation of a dirigible balloon. With 
the experience now acquired, the United States Government is in a 
position to proceed with the construction and operation of an air- 
ship worthy of comparison with any now in existence, but any efforts 
in this direction must await the action of Congress in providing the 
necessary funds. 

BALLOON PLANT AT FORT OMAHA, NEBRASKA 

96 In anticipation of taking up the subject of aeronautics on a 
scale commensurate with its importance, a complete plant has been 



PRESENT STATUS OF MILITARY AERONAUTICS 1591 

constructed at the Signal Corps post at Fort Omaha, Nebraska. 
This plant comprises a steel balloon house 200 ft. long, 84 ft. wide, 
and 75 ft. high; that is, large enough to house a dirigible balloon of 
the size of the new French Military Airship Le Republique. For 
furnishing hydrogen gas, an electrolytic plant has been installed 
capable of furnishing 3000 cu. ft. of gas per hour. A gasometer 
of 50 000 cu. ft. capacity has been provided to store a sufficient 
supply of gas for emergencies. 

97 In connection with the hydrogen plant, is a compressor for 
charging under pressure the steel tubes in which the gas is transported. 
A hydraulic pump for testing steel tubes at high pressure is a part of 
this equipment. A steel wireless telegraph tower 200 ft. high has 
been completed, and probably will be used in connection with wire- 
less experiments with dirigible balloons. 

Some General Considerations Which Govern the Design of 
a Dirigible Balloon 

buoyancy and shape 

98 Although many aerodynamic data are needed for the proper 
design of a dirigible airship, yet the experience already available in 
the construction and performance of such ships built on different 
plans is sufficient to enable the engineer to proceed with the design 
of a dirigible balloon to accomplish definite results along fairly accur- 
ate lines. In the case of this class of lighter-than-air ships the 
following general equation obtains: 

W - w = V (a - — ) (1) 



where 

W = weight of balloon, envelope, car, and aeronauts 

V = volume of balloon 

a = density of the air 

n = density of air as compared with gas 

weight of air displaced by car and aeronauts and 
envelope of balloon. 



w 



99 If we call the weight of the gas in the balloon M, then we can 
write this equation in the following manner: 

W + M = w + nM 



1592 PRESENT STATUS OF MILITARY AERONAUTICS 

from which we find that 

M = 

n -1 



M = W - W (2) 



and 



=("';■) („!-,> 



(3) 



thus obtaining the volume of gas required. If the volume of the 
gas-bag, car. aeronauts, etc. = v, then w = vo; so that (3) may be 
written 



V = 



I W - vo 
\ o 



I fc?rj 



100 Thus far, certainly, no dirigible balloon has ever been de- 
veloped which, has attained an independent speed greater than 40 
miles per hour. It will readily be admitted that an airship so designed 
as to reach a speed of 50 or 60 miles per hour would be regarded as a 
most decided step forward in the art. since this difference of velocity 
is just the increment needed to place such craft on a practical basis 
capable of maneuvering in the air in all ordinary weather. This 
advancement, although requiring much consideration, would fully 
compensate in practical results. 

101 The first point to be decided upon in the design of- an airship 
is the method of maintaining the shape of the gas-bag against the 
pressure encountered at the maximum velocity to be attained. 
There are two schools of design in this respect, each having its 
adherents. One maintains the shape of the gas-bag by a rigid 
interior frame, and the other by means of the internal pressure of 
the gas itself. 

102 Upon the selection of the type depends to a large extent the 
particular shape of the envelope. If the envelope is to maintain its 
shape by interior pressure of gas, evidently it must be so designed 
that the maximum pressure of the air developed at the speed contem- 
plated shall not be sufficient to cause deformation of any part of the 
envelope. This can be effected only by making the uniform internal 

ssure at least equal to the maximum external pressure. Since the 
maximum external pressure occurs over the prow of the air-ship, this 
evidently is the particular part which must receive most careful atten- 
tion with this system. 

103 The desirable shape of head would evidently be one where 
the distribution of external pressure due to air resistance at the 



PRESENT STATUS OF MILITARY AERONAUTICS 



1593 





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1594 PRESENT STATUS OF MILITARY AERONAUTICS 

velocity used is uniform. In addition to preventing deformation of 
the gas-bag, a prime requisite also is that the shape shall be such that 
the total resistance, comprising head resistance and skin-friction 
shall be a minimum for a given displacement and velocity. 

104 This immediately forces the question of the law of resistance 
of the air. On this subject there are numerous aerodynamic data 
for low velocities, and also for very high velocities, but such data are 
incomplete for the range of velocities here considered. 

105 In fact, the law of resistance of the air for surfaces of revo- 
lution as experimentally determined, is known to vary not with any 
constant power of the velocity, but by a range of exponents from the 
first to the cube, if not higher. For example, in the enormous A r eloci- 
ties attained by modern artillery, where bodies weighing a ton or 
more, are hurled through the air at 2000 ft. per second, it is known 
that the physical phenomena become entirely different in nature 
from those found when dealing with moderate velocities such as are 
met in transportation devices. 

RESISTANCE OF THE AIR TO THE MOTION OF A PROJECTILE 

106 In the expression for the retardation of oblong projectiles 
the velocity enters with an exponent, n, whose accepted values are 

as follows : 

Ft. per second Miles per hour 

n =,1 .55 for velocities greater than 2600 = 1773 

2600 and 1800 = 1773 and 1227 



n 


= 


1 


n 


= 


2 


n 


= 


3 


n 


= 


5 


n 


= 


3 


n 


= 


2 



for velocities between . 
for velocities between . 
for velocities between . 
for velocities between . 
for velocities between . 



1800 and 1370 = 1227 and 934 

1370 and 1230 = 934 and 836 

1230 and 970 = 836 and 639 

970 and 790 = 639 and 592 



for velocities less than . . . 790 = 592 

107 14-i??. and 16-m. Guns. The 14-in. guns fire a projectile 
weighing 1660 lbs. Service muzzle velocity 2150 f. s., which gives 
with an elevation of 15 deg. a range of 15 000 yds. 

108 The 16 in. guns fire a projectile weighing 2400 lbs. The 
Service muzzle velocity is 2150 f. s., or 1465 miles per hour, which 
gives, for an elevation of 15 deg. a range of 15 558 yd., or nearly 9 
miles. 

ANALOGY TO AIRSHIP 

109 Great guns are now constructed which throw masses of steei 
weighing as high as 2400 lb. to maximum distances approximating 



PRESENT STATUS OF MILITARY AERONAUTICS 1595 

15 to 20 miles, and with such high momentum that ordinary winds 
have little effect, as shown by the remarkable target practice of the 
Army and Navy. The shapes of these heavier-than-air flying 
machines are figures of revolution, and the longitudinal and lateral 
stability are maintained by imparting to the projectile a rotary 
motion about its longer axis by means of the rifling inside the bore 
of the gun. Such machines are 5000 or 6000 times heavier than 
air and travel at speeds far beyond any other engine constructed by 
man. No peripheral speeds attained with any machinery approach 
these velocities. 

110 It is noted that these projectile air-machines have a mass 
two and a half times that of the Wright Aeroplane, and attain a 
velocity through the air thirty-six times as great. 

111 It thus appears that the resistance of the air to the motion 
of bodies through it is in reality a complicated function of the velocity, 
and the best that can be said is that this velocity varies as a constant 
power only within certain limited ranges. In the velocities con- 
sidered for airships, it is approximate to regard the resistance as vary- 
ing as the square. 

112 As the velocity increases the form of the head becomes more 
and more important, and moderate velocities lead to a shape approxi- 
mating torpedo form, which is well known. In very high speed pro- 
jectiles the shape of the rear is not so important, since the velocity 
is so much greater than the velocity of sound in air, that a partial 
vacuum is formed behind the projectile which cannot well be obviated. 

113 If the rigid system be employed where an internal frame pre- 
vents deformation of the envelope, the stresses due to external pres- 
sure are taken up by the framework itself, and the gas required for 
flotation is usually contained in several separate receptacles or 
ballonets similar to compartments employed in ships. In this 
system, therefore, we are concerned only in securing such a shape of 
the rigid frame as will fulfill the condition of minimum total resistance 
for a given displacement and velocity. 

114 Once the shape of the bag is determined from the considera- 
tions already enumerated, the dimensions become immediately fixed 
when the tonnage is assumed, or conversely, if any linear dimension 
is assigned the tonnage is thereby determined. 

115 In addition to the two general systems above considered, 
there are various types involving some of the principles of each, 
which are classed in general as semi-rigid systems. Such systems 
usually comprise a rigid frame, to which is attached the gas-bag above, 
and the load below. 



1590 PRESENT STATUS OF MILITARY AERONAUTICS 

AERODYNAMIC ADJUSTMENTS 

1 16 The next step is one of structural design along strictly engi- 
neering lines. The aerodynamic features of airship construction 
may be considered under the heads: (a) static balance; (b) dynamic 
balance; (c) stability; (d) natural period and oscillation. 

117 Static Balance. The dimensions of the gas-bag being deter- 
mined, the lift of each transverse segment thereof is immediately 
known, and the design of the frame may proceed by approximate 
trial and correction as in other structural work. The weight of each 
segment of the envelope itself is readily computed, which added to 
the corresponding segment of the frame gives the total weight of 
each segment, and this total subtracted from the lift of each segment 
gives the net lift for that complete segment. From the magnitude 
and position of these net forces the position of the resultant lift is 
known, and this determines the vertical line through the center of 
gravity. Such procedure evidently insures static balance of the 
machine as a whole, and an approximate distribution of the load. 

118 Dynamic Balance. The dynamic balance must also be care- 
fully considered; and here a difficulty has been experienced on account 
of the inability to place the resultant thrust coincident with the line 
of resistance of the ship as a whole. Heretofore, it has been custo- 
mary to balance the thrust-resistance couple by means of suitable 
horizontal rudders or planes, so situated and at such angles, that the 
resultant moment of the system should be zero at uniform speeds of 
travel, though not necessarily zero for accelerated motion. 

119 If, however, the line of thrust be made coincident with the 
line of resistance, the disturbing moment in question will be eliminated 
at uniform speeds. If, furthermore, the center of mass be located 
on the line of thrust and sufficiently forward to form a righting couple 
with the resistance when the wind suddenly veers, the evil effects 
of a disturbing moment will be obviated for variable as well as for 
constant speeds. The ship is then dynamically balanced. 

120 This, of course, requires that the form of hull be such that a 
quartering wind shall exert a force passing to the rear of the center 
of mass. To illustrate, a good example of dynamic balance is found 
in a submarine torpedo, or a fish. 

121 Stability. The foregoing adjustments still allow the center 
of mass to be placed below the center of buoyancy. This is a provi- 
sion that is important in aeronautics as well as in marine archi- 
tecture, indeed it is the onl^y practical provision for keeping an even 



PRESENT STATUS OF MILITARY AERONAUTICS 1597 

keel and preventing heeling when the ship is at rest, or simply drifting 
with the wind. If the center of gravity b3 well below the center of 
buoyancy, the vessel is proportionately stable, but, of course, the 
stability is pendular, and may admit of considerable rolling and pitch- 
ing due to shifting loads, sudden gusts of wind, etc., unless special 
devices be used to dampen or prevent these effects. 

122 Natural Period and Oscillations. It may happen also that 
the equilibrium of the ship is disturbed by periodic forces whose 
periods are simply related to the natural period of the ship itself. 
In this case the oscillations will be cumulative and may become very 
large. Such effects are well known to marine engineers, and may be 
treated as in ordinary ship design. 

AVIATION 

123 This division comprises all those forms of heavier-than-air 
flying machines which depend for their support upon the dynamic 
reaction of the atmosphere. There are several subdivisions of this 
class dependent upon the particular principle of operation. Among 
these may be mentioned the aeroplane, orthopter, helicopter, etc. 
The only one of these that has been sufficiently developed at present 
to carry a man in practical flight is the aeroplane. There have been 
a large number of types of aeroplanes tested with more or less suc- 
cess and of these the following are selected for illustration. 

REPRESENTATIVE AEROPLANES OF VARIOUS TYPES 



124 The general conditions under which the Wright machine was 
built for the Government were, that it should develop a speed of at 
least 36 miles per hour, and in its trial flights remain continuously 
in the air for at least 1 hour. It was designed to carry two persons 
having a combined weight of 350 lb. and also sufficient fuel for a 
flight of 125 miles. The trials at Fort Myer, Virginia, in Septe ber 
of 1908, indicated that the machine was able to fulfill the require- 
ments of the government specifications. 

125 The aeroplane has two superposed main surfaces 6 ft. apart 
with a spread of 40 ft. and a distance of 6£ ft. from front to rear. 
The area of this double supporting surface is about 500 sq. ft. The 
surfaces are so constructed that their extremities may be warped at 
the will of the operator. 

126 A horizontal rudder of two superposed plane surfaces about 



1598 PRESENT STATUS OF MILITARY AERONAUTICS 

15 ft. long and 3 ft. wide is placed in front of the main surfaces. 
Behind the main pianos is a vertical rudder formed of two surfaces 
trussed together about 5V ft. long and 1 ft. wide. The auxiliary 
surfaces, and the mechanism controlling the warping of the main 
surfaces, are operated by three levers. 

127 The motor, which was designed by the Wright brothers, has 
four cylinders and is water cooled. It develops about 25 h.p. at 
1400 r.p.m. There are two wooden propellers 8-J ft. in ...diameter 
which are designed to run at about 400 r.p.m. The machine is sup- 
ported on two runners, and weighs about 800 lb. A monorail is 
used in starting. 

128 The Wright machine has attained an estimated maximum 
speed of about 40 miles per hour. On September 12, a few days 
before the accident which wrecked the machine, a record flight of 1 
hour, 14 minutes, 20 seconds was made at Fort Myer, Virginia. Since 
that date Wilbur Wright, at Le Mans, France, has made better 
records; on one occasion remaining in the air for more than an hour 
and a half with a passenger. 

129 A reference to the attached illustrations of this machine will 
show its details, its method of starting, and its appearance in flight. 

THE HERRING AEROPLANE 

130 The Signal Corps of the Army has contracted with A. M. 
Herring, of New York, to furnish an aeroplane under the conditions 
enumerated in the specification already referred to and shown in 
the appendix to this paper. Mr. Herring made technical delivery 
of his machine at the aeronautical testing ground at Fort Myer, 
Virginia, on October 13. 

131 In compliance with the request of Mr. Herring the details of 
this machine will not be made public at present, but the official tests 
required under the contract will be conducted in public as has been 
the case with other aeronautical devices. Opportunity will be afford- 
ed any one to observe the machine in operation. 

132 This machine embodies new features for automatic control 
and contains an engine of remarkable lightness per horse-power. 

THE FARMAN AEROPLANE 

133 The Farman flying machine has two superposed aerosurfaces 
4 ft. 11 in. apart with a spread of 42 ft. 9 in. and 6 ft. 7 in. from front 
to rear. The total sustaining surface is about 560 sq. ft. 



PRESENT STATUS OF MILITARY AERONAUTICS 1599 

134 A box tail 6 ft. 7 in. wide and 9 ft. 10 in. long in rear of the 
main surfaces is used to balance the machine. The vertical sides of 
the tail are pivoted along the front edges, and serve as a vertical rudder 
for steering in a horizontal plane. There are two parallel, vertical 
partitions near the middle of the main supporting surfaces, and one 
vertical partition in the middle of the box tail. A horizontal rudder 
in front of the machine is used to elevate or depress it in flight. 

135 The motor is an eight cylinder Antoinette of 50 h.p. weigh- 
ing 176 lb., and developing about 38 h.p. at 1050 r.p.m. 

136 The propeller is a built-up steel frame covered with aluminum 
sheeting, 1\ ft. in diameter, with a pitch of 4 ft. 7 in. It is mounted 
directly on the motor shaft immediately in rear of the middle of the 
main surfaces. 

137 The framework is of wood, covered with canvas. A chassis 
steel tubing carries two pneumatic-tired bicycle wheels. Two 
smaller wheels are placed under the tail. The total weight of the 
machine is 1166 lb. The main surfaces support a little over two 
pounds per square foot. The machine has shown a speed of about 
2S miles per hour and no starting apparatus is used. 

138 On January 13, 1908, Farman won the Grand Prix of the Aero 
Club of France in a flight of 1 minute and 28 seconds, in which he 
covered more than a kilometer. It is reported that on October 30, 
1908, a flight of 20 miles, from Mourmelon to Rheims, was made 
with this machine. 

THE BLERIOT AEROPLANE. 

139 Following Farman's first flight from town to town, M. Bleriot 
with his monoplane aeroplane made a flight from Toury to the 
neighborhood of Artenay and back, a total distance of about 28 kilo- 
meters. He landed twice during these flights and covered 14 kilo- 
meters of his journey in about 10 minutes, or attained a speed of 52 
miles an hour. 

THE JUNE BUG 

140 The June Bug was designed by the Aerial Experiment Asso- 
ciation, of which Alexander Graham Bell is President. It has two 
main superposed aerosurfaces with a spread of 42 ft. and 6 in., includ- 
ing wing tips, with a total supporting surface of 370 sq. ft. 

141 The tail is of the box type. The vertical rudder above the 
rear edge of the tail is 30 in. square. The horizontal rudder in front 
of the main surfaces is 30 in. wide by 8 ft. long. There are four 



1600 PRESENT STATUS OF MILITARY AERONAUTICS 

triangular wing tips pivoted along their front edges for maintaining 
transverse equilibrium. The vertical rudder is operated by a steering 
wheel, and the movable tips by cords attached to the body of the 
aviator. 

142 The motor is a 25 h.p., 8 cylinder, air cooled, Curtiss. The 
single wooden propeller immediately behind the main surfaces is 6 ft. 
2 in. in diameter and mounted directly on the motor shaft. It has 
a pitch angle of about 17 deg. and is designed to run at about 1200 
r.p.m. 

143 The total weight of the machine, with aviator, is 650 lb. 
It has a load of about If lb. per sq. ft. of supporting surface. Two 
pneumatic-tired bicycle wheels are attached to the lower part of the 
frame. 

144 With this machine, Mr. G. H. Curtiss, on July 4, 1908, won 
the Scientific American trophy by covering the distance of over a 
mile in 1 minute and 42f seconds at a speed of about 39 miles per 
hour. 

Some General Considerations Which Govern the Design 
of an Aeroplane 

145 The design of an aeroplane may be considered under the 
heads of support, resistance and propulsion, stability and control. 

146 Support. In this class of flying machines, since the buoyancy 
is practically insignificant, support must be obtained from the 
dynamic reaction of the atmosphere itself. In its simplest form, an 
aeroplane may be considered as a single plane surface moving through 
the air. The law of pressure on such a surface has been determined 
and may be expressed as follows: 

P = 2koAV 2 sm a (1) 

in which P is the normal pressure upon the plane, fc is a constant 
of figure, a the density of the air, A is the area of the plane. V the 
relative velocity of translation of the plane through the air. and a 
the angle of flight. 

147 This is the form taken by Duchemin's formula for small 
angles of flight such as are usually employed in practice. The equa- 
tion shows that the upward pressure on the plane varies directly with 
the area of the plane, with the sine of the angle of flight, with the 
density of the air, and also with the square of the velocity of trans- 
lation. 



PRESENT STATUS OF MILITARY AERONAUTICS 1601 

148 It is evident that the total upward pressure developed must 
be at least equal to the weight of the plane and its load, in order to 
support the system. If P is greater than the weight the machine will 
ascend, if less, it will descend. 

149 The constant k depends only upon the shape and aspect of 
the plane, and should be determined by experiment. For example, 
with a plane 1 foot square k a = 0.00167, as determined by Langley, 
when P is expressed in pounds per square foot, and V in feet per 
second. 

Equation (1) may be written 

P 



AV 



2 _ 



2 k a sin a 
If P and a are kept constant then the equation has the form 

A V 2 = constant. (2) 

PRINCIPLE OF REEFING IN AVIATION 

150 An interpretation of (2) reveals interesting relations. The 
supporting area varies inversely as the square of the velocity. For 
example, in the Wright aeroplane, the supporting area at 40 miles 
per hour is 500 sq. ft., while if the speed is increased to 60 miles 

500 

per hour this area need be only ^— - = 222 sq. ft., or less than one- 
half of its present size. At 80 miles per hour the area would be 
reduced to 125 sq. ft., and at 100 miles per hour only 80 sq. ft. of 
supporting area is required. These relations are conveniently 
exhibited graphically. 

151 It thus appears that if the angle of flight be kept constant in 
the Wright aeroplane, while the speed is increased to one hundred 
miles per hour, we may picture a machine which has a total support- 
ing area of 80 sq. ft., or a double surface each measuring about 2\ 
by 16 ft. or 4 by 10 ft. if preferred. Furthermore, the discarded 
mass of the 420 sq. ft. of the original supporting surface may be 
added to the weight of the motor and propellers in the design of a 
reduced aeroplane, since in this discussion the total mass is assumed 
constant at 1000 lb. 

152 In the case of a bird's flight, its wing surface is "reefed" as 
its velocity is increased, which instinctive action serves to reduce its 
head resistance and skin-frictional area, and the consequent power 
required for a particular speed. 



1602 PRESENT STATUS OF MILITARY AERONAUTICS 

153 Determination of k for Arched Surfaces. Since arched sur- 
faces are now commonly used in aeroplane construction, and as the 
above equation (1) applies to plane surfaces only, it is important to 
determine experimentally the value of the coefficient of figure k, for 
each type of arched surface employed, especially as k is shown in 
some cases to vary with the angle of flight a; i.e. the inclination of 
the chord of the surface to the line of translation. 

154 Assuming a constant, however, we may compare the lift 
of any particular arched surface with a plane surface of the same 
projected plan and angle of flight. 

155 To illustrate, in the case of the Wright aeroplane, let us 
assume 

P = 1000 lb. = total weight = W. 

A = 500 sq. ft. 

V = 40 miles per hour = 60 ft. per second. 

a = 7 deg. approximately. 

m 7 P 1000 

Whence ko = 



2 A V 2 sin a 2 X 500 X 60 2 X J 

= 0.0022 (V = ft. sec.) 
= 0.005 (V = mi. hr.) 

156 Comparing this value of k a with Langley's value 0.004 for 
a plane surface V being in miles per hour, we see that the lift for the 
arched surface is 25 per cent greater than for a plane surface of the 
same projected plan. That is to say, this arched surface is dynami- 
cally equivalent to a plane surface of 25 per cent greater area than 
the projected plan. Such a plane surface may be defined as the 
"equivalent plane. ,- ' 

157 Resistance and Propulsion. The resistance of the air to the 
motion of an aeroplane is composed of two parts: (a), the resistance 
due to the framing and load; (6), the necessary resistance of the sus- 
taining surfaces, that is, the drift, or horizontal component of pres- 
sure; and the unavoidable skin-friction. Disregarding the frame, 
and considering the aeroplane as a simple plane surface, we may 
express the resistance by the equation 

R = W tan a + 2 / A (3) 

in which R is the total resistance, W the gross weight sustained, a 
the angle of flight, / the friction per square unit of area of the plane, 



PEESENT STATUS OF MILITAEY AEEONAUTICS 



1603 



A the area of the plane. The first term of the second member gives 
the drift, the second term the skin-friction. The power required to 
propel the aeroplane is 

H = R V 

in which H is the power, V the velocity. 

158 Now W varies as the second power of the velocity, as shown 
by equation (1), and / varies as the power 1.85, as will be shown 
later. Hence we conclude that the total resistance R of the air to 
the aeroplane varies approximately as the square of its speed, and 
the propulsive power practically as the cube of speed. 

159 Most Advantageous Speed and Angle of Flight. Again, regard- 
ing W and A as constant, we may, by equation (1), compute a for 
various values of V, and find / for those velocities from the skin- 
friction table to be given presently. Thus a, R, and H may be 
found for various velocities of flight, and their magnitudes compared. 
In this way the values in Table 1 were computed for a soaring 
plane 1 ft. square weighing 1 lb., assuming k a = 0.004, which is 
approximately Langley's value wheu V is in miles per hour. 



COMPUTED POWER REQUIRED TO TOW A PLANE ONE FOOT SQUARE, 

WEIGHING ONE POUND, HORIZONTALLY THROUGH THE AIR AT 

VARIOUS SPEEDS AND ANGLES OF FLIGHT 



Velocity 


Angle 

of 
Flight 


COMPUTED RESISTANCE 


Tow-line 
power 


Lift per 

tow-line 

h.p. 




Drift 


Friction 


Total 


Mi. hr. 


Deg. 


Lb. 


Lb. 


Lb. 


Ft. lb. sec. 


Lb. 


30 


8.25 


0.145 


0.0170 


0.162 


7.13 


77.1 


35 


5.94 


0.104 


. 0226 


0.1266 


6.51 


84.3 


40 


4.52 


0.790 


0.0289 


0.1079 


6.32 


86.7 


45 


3.55 


0.0621 


0.0360 


0.0981 


6.39 


86.1 


50 


2.88 


0.0500 


0.0439 


0.0939 


6.89 


80.2 


60 


2.03 


0.0354 


0.0614 


0.0962 


8.50 


64.7 


70 


1.47 


0.0257 


0.0814 


0.1071 


11.00 


50.0 


SO 


1.12 


0.0195 


0.1045 


0.1240 


14.56 


35.8 


90 


0.88 


0.0154 


0.1300 


0.1454 


19.17 


28.7 


100 


0.71 


0.0124 


0.1584 


0.1708 


25.00 


22.0 



160 Column two, giving values of a for various speeds is com- 
puted from equation (1). Thus at 30 miles per hour, 

W 1 

sm a = = 

2 k a AV 3 2 X.004 X 1 X 30 2 

whence a = 8.25 deg. 



1604 



PRESENT STATUS OF MILITARY AERONAUTICS 




30 40 50 60 70 

VELOCITY-MILES PER HOUR= V. 



Figure A 



FOOT SQUARE PLANE WEIGHING ONE POUND 




2 3 4 5 

ANGLE OF FLIGHT-DEGREES 



Figure B 



PRESENT STATUS OF MILITARY AERONAUTICS 1605 

161 Column three is computed from the term W tan a in equa- 
tion (3), thus 

Drift = W tan a = 1 X tan 8.25 deg. = 0.145. 

162 Column four is computed from the term 2 f A, in equation 
(3), /being taken from the skin-friction table to be given presently. 

163 The table shows that if a thin plane 1 ft. square, weighing 
1 lb. be towed through the air so as just to float horizontally at 
various velocities and angles of flight, the total resistance becomes 
a minimum at an angle of slightly less than 3 deg., and at a velocity 
of about 50 miles per hour; also that the skin-friction approximately 
equals the drift at this angle. The table also shows that ithe pro- 
pulsive power for the given plane is a minimum at a speed of between 
40 and 45 miles per hour, the angle of flight then being approximately 
4.5 deg. 

164 The last column of the table shows that the maximum weight 
carried per horse-power is less than 90 lb. This horse-load may be 
increased by changing the foot square plane to a rectangular plane 
and towing it long-side foremost; also by lightening the load, and 
letting the plane glide at a lower speed; but best of all, perhaps, by 
arching it like a vulture's wing and also towing it long-side foremost 
as is the prevailing practice with aeroplanes. 

These relations are exhibited graphically in the diagrams, Figs. B, 
CandD. 

STABILITY AND CONTROL 

165 The question of stability is a serious one in aviation, especially 
as increased wind velocities are encountered. In machines of the 
aeroplane type there must be some means provided to secure fore 
and aft stability and also lateral stability. 

166 A large number of plans have been proposed for the accom- 
plishment of these ends, some based upon the skill of the aviator, 
others operated automatically, and still others employing a com- 
bination of both. At the present time no aeroplane has yet been 
publicly exhibited which is provided with automatic control. 
There is little difference of opinion as to the desirability of some form 
of automatic control. 

167 The Wright aeroplane does not attempt to accomplish this, 
but depends entirely upon the skill of the aviator to secure both 
lateral and longitudinal equilibrium, but it is understood that a 



1606 



PRESENT STATUS OF MILITARY AERONAUTICS 



FOOT SQUARE SOARING PLANE WEIGHING ONE POUND 

30 14444+444 1 1 h II I II IUU4J-IU-U-U-1— L44I ; ' i ; | :^_1^;X1-L1 1 I I : I I :;;; I 90 



U25 
Id 
(0 
(0 

CQ 

^20 



£l5 

O 

0. 



3 io 

i 

O 

h 
5 



i i 1 l 1 i fr i 1 1 1 ' 1 - ' i i : ' ; 

"f- -I- -}-]-t — ^ — • — " 

| lj|i;i[;4-i4j]i= s: 


in 

— -^ 


>- 

<f*r 




■ i i : r ; ■ ■ ■ 


/\ 



40 50 60 70 80 

VELOCITY- MILES PER HOUR 

Figure C 



i 
6 

604 

s 

0) 
«g 

z 

UJ 

z 

307 

o 



FOOT SQUARE SOARING PLANE WEIGHING ONE POUND 

TOW-LINE HORSE-LOAD.-LBS. 

I0 2030 40 5O6O7O6C90 




30 40 50 60 70 60 

VELOCITY,- MILES PER HOUR. 

Figure D 



ioo no 



PRESENT STATUS OF MILITARY AERONAUTICS 1607 

device for this purpose is one of the next to be brought forward by 
them. Much of the success of the Wright brothers has been due to 
their logical procedure in the development of the aeroplane, taking 
the essentials, step by step, rather than attempting every thing at 
once, as is so often the practice with inexperienced inventors. 

168 The aviator's task is much more difficult than that of the 
chauffeur. With the chauffeur, while it is true that it requires his 
constant attention to guide his machine, yet he is traveling on a 
roadway where he can have due warning through sight, of the turns 
and irregularities of the course. 

169 The fundamental difference between operating the aeroplane 
and the automobile, is that the former is traveling along an aerial 
highway which has manifold humps and ridges, eddies and gusts, 
and since the air is invisible he cannot see these irregularities and 
inequalities of his path, and consequently cannot provide for them 
until he has actually encountered them. He must feel the road 
since he cannot see it. 

170 Some form of automatic control whereby the machine itself 
promptly corrects for the inequalities of its path is evidently very 
desirable. As stated above, a large number of plans for doing this 
have been proposed, many of them based on gyrostatic action, mov- 
able side planes, revolving surfaces, warped surfaces, etc. A solu- 
tion of this problem may be considered as one of the next important 
steps forward in the development of the aeroplane. 

III. HYDROMECHANIC RELATIONS 

Some General Relations Between Ships in Air and Water 

171 At the present moment, so many minds are engaged upon 
the general problem of aerial navigation that any method by which 
a broad forecast of the subject can be made is particularly desirable. 
Each branch of the subject has its advocates, each believing implicitly 
in the superiority of his method. On the one hand the adherents of 
the dirigible balloon have little confidence in the future of the aero- 
plane, while another class have no energy to devote to the dirigible 
balloon, and still others prefer to work on the pure helicopter princi- 
ple. As a matter of fact, each of these types is probably of per- 
manent importance, and each particularly adapted to certain needs. 

172 Fortunately for the development of each type, the experi- 
ments made with one class are of value to the other classes, and these 



1608 PRESENT STATUS OF MILITARY AERONAUTICS 

in turn bear close analogy to the types of boats used in marine navi- 
gation. The dynamical properties of water and air are very much 
alike, and the equations of motion are similar for the two fluids, so 
that the data obtained from experiments in water, which are very 
extensive, may with slight modification be applied to computations for 
aerial navigation. 

173 Helmholz' Theorem. Von Helmholz, the master physicist 
of Germany, who illuminated everything he touched, has fortunately 
considered this subject, in a paper written in 1873. The title of his 
paper is "On a theorem relative to movements that are geometrically 
similar in fluid bodies, together with an application to the problem of 
steering balloons." 

174 In this paper Helmholz affirms that, although the differen- 
tial equations of hydro-mechanics may be an exact expression of 
the laws controlling the motions of fluids, still it is only for relatively 
few and simple experimental cases that we can obtain integrals 
appropriate to the given conditions, particularly if the cases involve 
viscosity and surfaces of discontinuity. 

175 Hence, in dealing practically with the motion of fluids, we 
must depend upon experiment almost entirely, often being able to 
predict very little from theory, and that usually with uncertainty. 
Without integrating, however, he applies the hydrodynamic equa- 
tions to transfer the observations made on any one fluid with given 
models and speeds, over to a geometrically similar mass of another 
fluid involving other speeds, and models of different magnitudes. 
By this means he is able to compute the size, velocity, resistance, 
power, etc., of aerial craft from given, or observed, values for marine 
craft. 

176 He also deduces laws that must inevitably place a limit upon 
the possible size and velocity of aerial craft without, however, indi- 
cating what that limit may be with artificial power. Applying this 
mode of reasoning to large birds he concludes by saying that. "It 
therefore appears probable that in the model of the great vulture. 
nature ha* already reached the limit that can be attained with the 
muscles as working organs, and under the most favorable conditions 
of subsistence, for the magnitude of a creature that shall raise itself 
by its wings and remain a long time in the air." 

177 In comparing the behavior of models in water and air. he 
takes account of the density and viscosity of the media, as these were 
well known at the date of his writing, 1S73; but he could not take 
account of the sliding, or skin-friction, because in his day neither 



PRESENT STATUS OF MILITARY AERONAUTICS 



1609 



the magnitude of such friction for air, nor the law of its variation 
with velocity had been determined. 

SKIN-FRICTION IN AIR 

178 Even as late as Langley's experiments, skin-friction in air 
was regarded as a negligible quantity, but due to the work of Dr. Zahm 
who was the first to make any really extensive and reliable experi- 
ments on skin-friction in air, we now can estimate the magnitude of 
this quantity. As a result of his research he has given in his paper 
on atmospheric friction the following equation: 



/ = 0.00000778 I 

f = 0.0000158 r°-°j, 



,1.85 



(v = ft. sec), 
(v = mi. hr.) 



in which / is the average skin-friction per square foot, and I the length 
of surface. 

179 From this equation the accompanying table of resistances 
was computed, and is inserted here for the convenience of Engineers: 



TABLE 2 



FRICTION PER SQUARE FOOT FOR VARIOUS SPEEDS AND 
LENGTHS OF SURFACE 







Average 


Friction in 


Pounds per Square Foot 




Wind 














speed 


1 ft. plane 


2 ft. plane 


4 ft. plane 


8 ft. plane 


16 ft. plane 


32 ft. plane 


mi. hr. 


0.000303 












5 


0.000289 


0.000275 


. 000262 


0.000250 


. 000238 


10 


0.00112 


0.00105 


0.00101 


0.000967 


0.000922 


0.000878 


15 


0.00237 


0.00226 


0.00215 


0.00205 


0.00195 


0.00186 


20 


0.00402 


0.00384 


. 00365 


0.00349 


0.00332 


0.00317 


25 


0.00606 
0.00S50 


0.00579 


0.00551 


0.00527 


0.00501 


0.00478 


30 


0.00810 


0.00772 


0.00736 


0.00701 


0.00668 


35 


0.01130 


0.0108 


0.0103 


0.0098 


. 00932 


0.00888 


40 


0.0145 


0.0138 


0.0132 


0.0125 


0.0125 


0.0114 


50 


0.0219 


0.0209 


0.0199 


0.0190 


0.0181 


0.0172 


60 


0.0307 


. 0293 


0.0279 


0.0265 


0.0253 


0.0242 


70 


0.0407 


0.0390 


0.0370 


0.0353 


0.0337 


0.0321 


80 


0.0522 


0.0500 


0.0474 


0.0452 


0.0431 


0.0411 


90 


0.0650 


0.0621 


0.0590 


0.0563 


0.0536 


0.0511 


100 


0.0792 


0.0755 


0.0719 


0.0685 


0.0652 


0.0622 



180 The numbers within the rules represent data coming within 
the range of observation. These observations show that "the 
frictional resistance is at least as great for air as water, in proportion 
to their densities. In other words, it amounts to a decided obstacle 



1610 PRESENT STATUS OF MILITARY AERONAUTICS 

in high speed transportation. In aeronautics it is one of the chief 
elements of resistance both to hull-shaped bodies and to aero-sur- 
faces gliding at small angles of flight." 

181 Relative Dynamic and Buoyant Support. Peter Cooper- 
Hewitt has given careful study to the relative behavior of ships in 
air and in water. He has made a special study of hydroplanes, and 
has prepared graphic representations of his results which furnish a 
valuable forecast of the problem of flight. 

182 Without knowing of Helmholz's theorem, Cooper-Hewitt 
has independently computed curves for ships and hydroplanes from 
actual data in water, and has employed these curves to solve analo- 
gous problems in air, using the relative densities of the two media, 
approximately 800 to 1, in order to determine the relative values 
of support by dynamic reaction and by displacement for various 
weights and speeds. 

183 An analysis of these curves leadsto conclusions of importance, 
some of which are as follows: 

184 The power consumed in propelling a displacement vessel at 
any constant speed, supported by air or w T ater, is considered as being 
§ consumed by skin-resistance, or surface resistance, and J consumed 
by head resistance. Such a vessel will be about ten diameters in 
length, or should be of such shape that the sum of the power con- 
sumed in surface friction and in head resistance will be a minimum 
(torpedo shape). 

185 The power required to overcome friction due to forward 
movement will be about J as much for a vessel in air as for a vessel of 
the same weight in water. 

186 Leaving other things out of consideration, higher speeds can 
be obtained in craft of small tonnage by the dynamic reaction type 
than by the displacement type, for large tonnages the advantages of 
the displacement of type are manifest. 

187 A dirigible balloon carrying the same weight, other things 
being equal, may be made to travel about twice as fast as a boat for 
the same power; or be made to travel at the same speed with the 
expenditure of about £ of the power. 

188 As there are practically always currents in the air reaching 
at times, a velocity of many miles per hour, a dirigible balloon should 
be constructed with sufficient power to be able to travel at a speed 
of about 50 miles per hour, in order that it may be available under 
practical conditions of weather. In other words, it should have 
substantially as much power as would drive a boat, carrying the same 



PRESENT STATUS OF MILITARY AERONAUTICS 1611 

weight, 25 miles an hour, or should have the same ratio of power to 
size as the "Lusitania." 

189 Motors. It is the general opinion that any one of several 
types of internal combustion motors at present available is suitable 
for use with dirigible balloons. With this type, lightness need not 
be obtained at the sacrifice of efficiency. In the aeroplane, however, 
lightness per output is a prime consideration, and certainty and 
reliability of action is demanded, since if by chance the motor stops, 
the machine must immediately glide to the earth. A technical dis- 
cussion of motors would of itself require an extended paper, and 
may well form the subject of a special communication. 

190 Propellers. The fundamental principles of propellers are the 
same for air as for water. In both elements, the thrust is directly 
proportional to the mass of fluid set in motion per second. A great 
variety of types of propellers have been devised, but, thus far only 
the screw-propeller has proved to be of practical value in air. The 
theory of the screw-propeller in air is substantially the same as for 
the deeply submerged screw-propeller in water, and therefore does not 
seem to call for treatment here. There is much need at present for 
accurate aerodynamic data on the behavior of screw-propellers in 
air, and it is hoped that engineers will soon secure such data, and present 
it in practical form for the use of those interested in airship design. 

191 Limitations. Euclid's familiar "square-cube" theorem con- 
necting the volumes and surfaces of similar figures, as is well known, 
operates in favor of increased size of dirigibles, and limits the possible 
size of heavier-than-air machines in single units and with concen- 
trated load. 

192 It appears, however, that both fundamental forms of aerial 
craft will likely be developed, and that the lighter-than-air type will 
be the burden-bearing machine of the future, whereas the heavier- 
than-air type will be limited to comparatively low tonnage, operating 
at relatively high velocity. The helicopter type of machine may be 
considered as the limit of the aeroplane, when by constantly increas- 
ing the speed, the area of the supporting surfaces is continuously 
reduced until it practically disappears. We may then picture a 
racing aeroplane propelled by great power, supported largely by the 
pressure against its body, and with its wings reduced to mere fins 
which serve to guide and steady its motion. In other words, start- 
ing with the aeroplane type; we have the dirigible balloon on the one 
hand as the tonnage increases, and the helicopter type on the other 
extreme as the speed increases. Apparently, therefore, no one of 



1612 PRESENT STATUS OF MILITARY AERONAUTICS 

these forms will be exclusively used, but each will have its place for 
the particular work required. 

IV. AERIAL LOCOMOTION IN WARFARE 

193 Whatever may be the influence of aerial navigation upon the 
Art of War, the fact which must be considered at present is, that 
each of the principal Military Powers is displaying feverish activity 
in developing this auxiliary as an adjunct to the military establish- 
ment. 

194 If each of the great Powers of the world would agree that 
aerial warfare should not be carried on, the subject would be of no 
great interest to this country as far as our military policy is concerned, 
but until such an agreement is made this country is forced to an 
immediate and serious consideration of this subject in order to be 
prepared for any eventuality. 

195 The identical reasoning which has led to the adoption of a 
policy of providing for increasing our Navy year by year to main- 
tain our relative supremacy on the sea, is immediately applicable to 
the military control of the air. If the policy in respect to the Navy 
is admitted, there is no escape from the deduction that we should 
proceed in the development of ships of the air on a scale commen- 
surate with the position of the Nation. 

196 The question as to whether or not the Powers will ultimately 
permit the use of aerial ships in war is not at present the practical 
one, because in case such use is authorized it will be too late ade- 
quately to equip ourselves after war has been declared. 

ACTION OF THE HAGUE PEACE CONFERENCE 

197 The following is the declaration signed by the delegates of 
the United States to the Second International Peace Conference held 
at The Hague, June 15 to October 19. 1907. prohibiting the discharge 
of projectiles and explosives from balloons, ratified March 10. 190S. 

19S Declaration: 

TJie Contracting Powers agree to prohibit, for a period extending to 
the close of the Third Peace Conference, the discharge of projectiles 
and explosives from balloons or by other new methods of a similar nature. 

199" The delegates of the United States signed this declaration. 
The countries which did not sign the declaration forbidding the 
launching of projectiles and explosives from balloons were: Germany, 



PRESENT STATUS OF MILITARY AERONAUTICS 1613 

Austria-Hungary, China, Denmark, Ecuador, Spain, France, Great 
Britain, Guatemala, Italy, Japan, Mexico, Montenegro, Nicaragua, 
Paraguay, Roumania, Russia, Servia, Sweden, Switzerland, Turkey, 
Venezuela. 

200 It appears that the United States is the only first-class Power 
who signed this agreement, and an analysis of the text of the agree- 
ment itself shows that no serious attempt was made to settle the 
question finally. 

201 For instance, while the war balloon may not discharge pro- 
jectiles or explosives from above, yet no reciprocal provision is aiade 
preventing such war balloon from being fired upon from the earth 
below, yet the law of self-defense evidently obtains. 

202 Furthermore, Naval Experts will tell you that they fear no 
enemy quite as much as a submarine mine, whose location is unknown 
and which gives no warning when it is approached. Our own 
experience shows that the Battleship Maine could be completely 
destroyed in time of peace without any one detecting the preparations 
for its accomplishment. 

203 If, then, a nation can submerge a mine for the destruction of 
ships from underneath the water, why can it not drop an aerial mine 
upon a ship from above? And if it should be allowed to drop an 
aerial mine upon an enemy's fortified ship at sea, it certainly should 
be allowed to drop such an aerial mine upon a fortified place on 
land. 

INFLUENCE ON THE MILITARY ART 

204 The Military Art up to the present time, has been practically 
conducted in a plane where the armies concerned have been limited 
in their movements in time and place by the physical character of 
the terrane. A large army, for instance cannot move faster than 
about 12 miles a day by marching, and the use of railroads as applied 
to the Art of War was first recognized in the Franco-Prussian war. 
By their use, the mobilization of the great Prussian army, and its 
accurate assembling in the theater of operations within ten days, 
contributed an initial advantage not before possible. 

205 The very essence of strategy is surprise, and there never were 
better opportunities than at present for a constructive General to 
achieve great victories. But these victories to be really great, must 
be founded upon some new development or use of power not here- 
tofore known in war. They must also tend to produce results with 
the minimum loss of human life. In other words, the sentiment of 



1614 PRESENT STATUS OF MILITARY AERONAUTICS 

the world demands that the Military Art shall always aim to capture, 
not destroy. 

206 It may be said, that the consummation of Military Art is 
found in maneuvering the enemy into untenable situations / thereby 
forcing a decisive result with a minimum loss of life and treasure. 

207 As to the technical use of dirigible balloons and aeroplanes 
in warfare we have nothing but theory at present to guide us. It 
would appear, however, in the case of dirigible balloons that two 
different classes of such ships should be developed. 

208 First: A comparatively small dirigible type with a capacity 
of from 50 000 to 100 000 cubic feet, to be used principally for 
scouting purposes and to a limited extent for carrying explosives 
for demolitions or for incendiary purposes, such as destroying bridges 
and supply depots close to the mobile army or coast defense fortress. 
In reconnoitering dirigibles of this class, in order to be safe during 
day-time they will have to maneuver at an altitude of about a mile, 
but experiments show that telephotographic apparatus will operate 
from this height to give much detail. 

209 At night, such dirigibles may descend to within a few hun- 
dred feet of the ground with safety and thus obtain much valuable 
information. Equipped with wireless telegraph or telephone appar- 
atus, military data could be obtained and transmitted without 
undue risk. Due to the small carrying capacity of such sizes, the 
radius of action would probably be limited at present to about two 
hundred miles. 

210 Second: This type of dirigible maybe developed for burden- 
bearing purposes. It has been pointed out above that the larger 
the airship the greater the speed it may be given, and the greater 
its radius of action. There is no reason to doubt, that airships 
capacity, from 500 000 to 1 000 000 cubic feet may be ultimately 
developed to attain speeds of 50 to 75 miles per hour. With a 
capacity for such speed, the aerial craft becomes a powerful practical 
engine of war which may be used in all ordinary weather. By keep- 
ing high in the air in day-time, and descending at night, they may 
launch high explosives, producing great damage. Being able to 
pass over armies and proceed at great speeds, their objectives would 
not usually be the enemy's armies, but their efforts would be directed 
against his base of supplies; to destroy his dry-docks, arsenals, ammu- 
nition depots, principal railway centers, storehouses, and indeed 
the enemy's Navy itself. 



PRESENT STATUS OF MILITARY AERONAUTICS 1615 

211 It is thought that there will be little difficulty in launching 
explosives with accuracy, provided good maps and plans are available. 
Due to the small cost of such ships as compared with naval vessels, 
the risk of loss would be readily taken. 

212 The element of time has always been a controlling factor in 
warfare. It is often a military necessity to conduct a reconnoissance 
in force to develop the enemy's dispositions. This requires at times 
a detachment of several thousand men from the main army, for a 
considerable period of time to accomplish this end. With efficient 
military airships, these results may be attained with a very few men 
in a small fraction of the time heretofore required. 

213 Delimitation of Frontiers. The realization of aerial naviga- 
tion for military purposes, brings forward new questions regarding the 
limitation of frontiers. As long as military operations are confined 
to the surface of the earth, it has been the custom to protect the 
geographical limits of a country by ample preparations in time of 
peace, such as a line of fortresses properly garrisoned. At the out- 
break of war these boundaries represent real and definite limits to 
military operations. Excursions into the enemy's territory usually 
require the backing of a strong military force. Under the new con- 
ditions, however, these geographic boundaries no longer offer the 
same definite limits to military movements. With a third dimension 
added to the theater of operations, it will be possible to pass over 
this boundary on rapid raids for obtaining information, accomplish- 
ing demolitions, etc., returning to safe harbors in a minimum time. 
We may, therefore, regard the advent of military ships of the air, as, 
in a measure, obliterating present national frontiers in conducting 
military operations. 

214 One of the military objectives in warfare, is usually the 
enemy's capital city, his ministers, and his chief Executive. This 
objective has heretofore been protected by large armies of soldiers, 
who, in themselves are not so important to the result. In order 
to attain the objective, it has been frequently necessary to subdue 
large numbers of soldiers needlessly. 

215 With the advent of efficient ships of the air, however, small 
parties may pass over these protective armies on expeditions aimed 
at the seat of government itself, where reside the body of particular 
individuals most responsible, so that the ultimate result will be to 
deter a rash entrance into war for personal ends; since now for the 
first time responsible individuals of state may be in immediate and 
personal danger after the declaration of war, which heretofore has 
not been usually the case. 



1616 PRESENT STATUS OF MILITARY AERONAUTICS 

INTERIOR HARBORS 

216 In the development of these larger types of dirigible balloons 
the main difficulty will be ; in providing suitable harbors or places of 
safety, for replenishing supplies and for seeking shelter in times of 
stress. As long as the dirigible balloon remains in the air it may be 
regarded as tolerably safe, both in itself, and as a conveyance for 
observers. If it's engines are disabled, it is at least a free balloon and 
may be operated as such. 

217 When brought in contact with the ground, however, it is 
in considerable danger from high winds. The momentum of such 
an enormous airship is great, and the comparatively fragile structure 
of the craft makes it an easy prey to the pounding which it is likely 
to receive when landing. Just as marine ships must seek a sheltered 
harbor or put to the open sea in times of storm, so in case of ships 
of the air, it is much more necessary either to brave the storm in the 
open, or to seek some sheltered harbor on land. 

218 Fortunately, in this case, certain suitable harbors for very 
large ships may be provided at small expense, by using narrow and 
deep valleys and ravines, surrounded by forests or other protection, 
or prepared railway cuts, etc., where the airship may descend and 
be reasonably safe from the winds above. These harbors should, 
of course, be known to the pilot, and carefully plotted on his maps 
beforehand. The compass bearings of each harbor from prominent 
points on land must be known and plotted, to assist as far as possible 
in navigating the airship in thick weather; and such harbors may be 
indicated to the pilot at night by vertical searchlight beams, or by 
suitable rockets, etc. 

219 The aeroplane, as has been pointed out. is likely to prove a 
flying machine of comparatively low tonnage and high speed. It is 
not likely to become a burden-bearing ship, at least in single units, 
but will be extremely useful for reconnoitering purposes; for dis- 
patching important orders and instructions at high speed; for reach- 
ing inaccessible points; or for carrying individuals of high rank and 
command to points where their personality is needed. 

220 One of the bloodiest contests the world has ever seen, was 
the Japanese attack on** 203 Meter Hill," yet, the sole object of this 
great slaughter, was for the purpose of placing two or three men at 
its summit to direct the fire of the Japanese siege guns upon the 
Russian fleet in the harbor at Port Arthur. 

221 If the United States had possessed in 1898, a single dirigible 



PRESENT STATUS OF MILITARY AERONAUTICS 1617 

balloon, even of the size of the one now at Fort Myer, Virginia, which 
cost less than $10 000, the American Army and Navy would not 
have long remained in doubt of the presence of Cervera's fleet in 
Santiago Harbor. 

222 The world is undoubtedly growing more humane year by 
year. We have arrived at a conception of the principle of an efficient 
Army and Navy, not to provoke war but to preserve peace, and it 
is believed, that, following this principle, the perfection of ships of 
the air for military purposes will materially contribute, on the whole, 
to make war less likely in the future than in the past. 



APPENDIX NO. 1 

SIGNAL CORPS SPECIFICATION, NO. 486 

Advertisement and Specification for a Heavier-thax-Air Flying 

Machine. 
To the Public: 

Sealed proposals, in duplicate, will be received at this office until 12 o'clock 
noon on February 1, 1908, on behalf of the Board of Ordnance and Fortification 
for furnishing the Signal Corps with a heavier-than-air flying machine. All 
proposals received will be turned over to the Board of Ordnance and Fortifica- 
tion at its first meeting after February 1 for its official action. 

Persons wishing to submit proposals under this specification can obtain the 
necessary forms and envelopes by application to the Chief Signal Officer. United 
States Army, War Department, Washington, D. C. The United Stat< - 
the right to reject any and all proposals. 

Unless the bidders are also the manufacturers of the flying machine they must 
state the name and place of the maker. 

Preliminary. — This specification covers the construction of a flying machine 
supported entirely by the dynamic reaction of the atmosphere and having no uas 
bag. 

Acceptance. — The flying machine will be accepted only after a successful trial 

flight, during which it will comply with all requirements of this specification. 

No payments on account will he made until after the trial flight and acceptance. 

Inspection. — The Government reserves the right to inspect any and all proc - - 

of manufacture. 

GENERAL REQUIREMENTS. 

The general dimensions of the living machine will be determined by the man- 
ufacturer, subject to the following conditions: 

1. Bidders must submit with their proposal- the following: 

(a) Drawings to scale showing the general dimensions and shape of the 

flying machine which they propose to build under this specification. 

(b) Statement of the speed for which it is designed. 

(c) Statement oi the total surface area of the supporting planes. 

(d) Statement of the total weight. 

(e) Description of the engine which will be used for motive power. 

(/) The material of which the frame, planes, and propellers will be con- 
structed. Plans received will not be shown to other bidders. 

2. It is desirable that the riving machine should be designed so that it may be 
quickly and easily assembled and taken apart and packed for transportation in 
army wagons. It should be capable of being assembled and put in operating 
condition in about one hour. 



PRESENT STATUS OF MILITARY AERONAUTICS 1619 

3. The flying machine must be designed to carry two persons having a com- 
bined weight of about 350 pounds, also sufficient fuel for a flight of 125 miles. 

4. The flying machine should be designed to have a speed of at least forty 
miles per hour in still air, but bidders must submit quotations in their proposals 
for cost depending upon the speed attained during the trial flight, according to the 
following scale ; 

40 miles per hour, 100 per cent. 
39 miles per hour, 90 per cent. 
38 miles per hour, 80. per cent. 
37 miles per hour, 70 per cent. 
36 miles per hour, 60 



36 miles per hour, 60 per cent. 
Less than 36 miles per hour rejected. 

41 miles per hour, 110 per cent. 

42 miles per hour, 120 per cent. 

43 miles per hour, 130 per cent. 

44 miles per hour, 140 per cent. 



5. The speed accomplished during the trial flight will be determined by taking 
an average of the time over a measured course of more than five miles, against and 
with the wind. The time will be taken by a flying start, passing the starting point 
at full speed at both ends of the course. This test subject to such addi- 
tional details as the Chief Signal Officer of the Army may prescribe at the time. 

6. Before acceptance a trial endurance flight will be required of at least one 
hour during which time the flying machine must remain continuously in the air 
without landing. It shall return to the starting point and land without any 
damage that would prevent it immediately starting upon another flight. During 
this trial flight of one hour it must be steered in all directions without difficulty 
and at all times under perfect control and equilibrium. 

7. Three trials will be allowed for speed as provided for in paragraphs 4 and 
5. Three trials for endurance as provided for in paragraph 6, and both tests must 
be completed within a period of thirty days from the date of delivery. The 
expense of the tests to be borne by the manufacturer. The place of delivery to 
the Government and trial flights will be at Fort Myer, Virginia. 

8. It should be so designed as to ascend in any country which may be encoun- 
tered in field service. The starting device must be simple and transportable. It 
should also land in a field without requiring a specially prepared spot and without 
damaging its structure. 

9. It should be provided with some device to permit of a safe descent in case 
of an accident to the propelling machinery. 

10. It should be sufficiently simple in its construction and operation to per- 
mit an intelligent man to become proficient in its use within a reasonable length of 
time. 

11. Bidders must furnish evidence that the Government of the United States 
has the lawful right to use all patented devices or appurtenances which may be a 
part of the flying machine, and that the manufacturers of the flying machine are 
authorized to convey the same to the Government. This refers to the unre- 
stricted right to use the flying machine sold to the Government, but does not 
contemplate the exclusive purchase of patent rights for duplicating the flying 
machine. 



1620 PRESENT STATUS OF MILITARY AERONAUTICS 

12. Bidders will be required to furnish with their proposal a certified check 
amounting to ten per cent of the price stated for the 40-mile speed. Upon making 
the award for this flying machine these certified checks will be returned to the 
bidders, and the successful bidder will be required to furnish a bond, according to 
Army Regulations, of the amount equal to the price stated for the 40-mile speed. 

13. The price quoted in proposals must be understood to include the instruc- 
tion of two men in the handling and operation of this flying machine. No extra 
charge for this service will be allowed. 

14. Bidders must state the time which will be required for delivery after 
receipt of order. 

JAMES ALLEX 
Brigadier General, Chief Signal Officer of the Army 
Signal Office, 

Washington, D. C, December 28, 1907 



APPENDIX NO. 2 

SIGNAL CORPS SPECIFICATION, NO. 483. 
Advertisement and Specification for a Dirigible Balloon. 

Bidders are requested to read carefully every paragraph of this specification and 
include in their proposal every detail called for. 

To the public. — Sealed proposals, in duplicate, will be received at this office 
until 12 o'clock noon on February 15, 1908, and no proposals will be considered 
which are received after that hour. 

Persons wishing to submit proposals under this specification can obtain the 
necessary forms and envelopes by application to the Chief Signal Officer, United 
States Army, War Department, Washington, D.C. The United States reserves the 
right to reject any and all proposals. 

Unless the bidders are also the manufacturers of the dirigible balloon they 
must state the name and place of the maker. 

Preliminary. — This specification covers the construction of a dirigible balloon, 
to consist of a gas bag supporting a suitable framework on which will be mounted 
the necessary propelling machinery. 

Inspection. — The Chief Signal Officer of the Army will reserve the right to 
inspect any and all processes of manufacture, and unsatisfactory material will 
be marked for rejection by the inspectors before assembling. 

Acceptance. — The dirigible balloon will be accepted only after a trial flight, 
during which it will comply with all requirements of this specification. 

GENERAL REQUIREMENTS. 

The general dimensions of the dirigible balloon will be determined by the 
manufacturer, subject to the following conditions: 

1. The gas bag shall be designed for inflation with hydrogen. The material 
for the gas bag shall be furnished by the bidder, and shall be subject to approval 
by the Chief Signal Officer of the Army, and must have a minimum breaking 
strength of not less than 62 § pounds per inch width and must require no varnish. 
The dimensions and shape of the gas bag will be as desired by the manufacturer, 
except that the length must not exceed one hundred and twenty (120) feet. 

2. Inside the gas bag there will be either one or two ballonets having a total 
capacity of at least one-sixth the total volume of the gas bag. Leading to the 
ballonets there will be tubes of proper size connected to a suitable centrifugal 
blower for maintaining a constant air pressure in the ballonets. The approved 
fabric for the ballonets must have a minimum tensile strength of not less than 48$ 
pounds per inch width. 

3. Valves. — In the lower part of the ballonet and gas bag, or on the ballonet 
air tubes near the gas bag, there will be an adjustable automatic valve designed 



1622 PRESENT STATUS OF MILITARY AERONAUTICS 

to release air from the ballonet to the outside atmosphere. On the under side of 
the gas bag there will be a second adjustable automatic valve of suitable size, so 
designed as to release hydrogen from the interior of the gas bag to the outside 
atmosphere. This valve will also be arranged so that it may be opened at will 
by the pilot. 

4. In the upper portion of the gas bag there will be provided a ripping strip 
covering an opening five (5) inches wide by six (6) feet long, with a red rip cord 
attached in the usual manner and brought down within reach of the pilot through 
a suitable gas-tight rubber plug inserted in a wooden ring socket. 

5. The suspension system and frame must be designed to have a factor of 
safety of at least three, taking into account wind strains as well as the weight 
suspended. 

6. A type of frame which can be quickly and easily assembled and taken 
apart will be considered an advantage. 

7. The balloon must be designed to carry two persons having a combined 
weight of 350 pounds; also at least 100 pounds of ballast, which may be used to 
compensate for increased weight of balloon when operating in rain. 

8. The dirigible balloon should be designed to have a speed of tw< my miles 
per hour in still air, but bidders must submit quotation- in their prop* sals for 
cost depending upon the speed attained during the trial flight acoruing to the 
following schedule: 



20 miles per hour, 100 per cent. 
19 miles per hour, 85 per cent. 
18 miles per hour, 70 per cent. 
17 miles per hour, 55 per cent. 
1G miles per hour, 40 per cent. 
Less than 16 miles per hour rejected. 

21 miles per hour, 115 per cent. 

22 miles per hour, 130 per cent. 

23 miles per hour. 145 per cent. 

24 miles per hour, 160 per cent. 



9. The speed accomplished during the trial flight will be determined by taking 
an average of the time over a measured course o( between two and five miles 
against and with the wind. The time will be taken by a flying start, passing the 
starting point at full speed at both ends oi the course. This test subject to such 
additional details as the Chief Signal Officer of the Army may prescribe at the 
time. 

10. Provision must be made to carry sufficient fuel tor continuous operation of 
the engine for at least two hours. This will be determined by a trial endurance 
flight of two hours, during which time the airship will travel continuously at an 
average speed of at least 70 per cent of that which the airship accomplishes during 
the trial flight for speed stated in paragraph 9 of this specification. The engine 
must have suitable cooling arrangements, so that excessive heating will not occur. 

11. Three trials will be allowed for speed as provided for in paragraph 9, 
and three trials for endurance as provided for in paragraph 10. and both tests 
must be completed within a period of thirty days frcm the date of delivery. 
the expense of the tests to be borne by the manufacturer. The place 

to the Government and trial flights will be at Fort Mver. Virginia. 



PRESENT STATUS OF MILITARY AERONAUTICS 1623 

12. The scheme for ascending and descending and maintaining equilibrium 
must be regulated by shifting weights, movable planes, using two ballonets or other 
approved method. Balancing by the aeronaut changing his position will not be 
accepted. 

13. This dirigible balloon will be provided with a rudder of suitable size, a 
manometer for indicating the pressure within the gas bag, and all other fittings 
and appurtenances which will be required for successful and continuous flights, 
according to this specification. 

14. Bidders will be required to furnish with their proposal a certified check 
amounting to fifteen per cent of the price stated for the 20-mile speed. Upon 
making the award for this airship these certified checks will be returned to bidders, 
and the succpssful bidder will be required to furnish a bond, according to Army 
Regulations, of the amount equal to the price stated for 20-mile speed. 

15. Bidders must submit with their proposals drawings to scale showing the 
general dimensions and shape of the dirigible balloon which they propose to build 
under this specification ; the horsepower and description of the engine which will 
be used for the motive power; the size, pitch and number of revolutions of the pro- 
pellers; drawing illustrating the suspension system for attaching frame to gas bag; 
horse power and description of blower for forcing air into ballonets; volume of 
gas bag; volume of ballonets; the material of which the frame will be constructed; 
size of valves., etc. Plans rec ived will not be shown to other bidders. 

16. Bidders must furnish evidence that the Government of the United States 
has the lawful right to use all patented devices or appurtenances which may be 
part of the dirigible balloon and that the manufacturers of the dirigible bal- 
loon are authorized to convey the same to the Government. This refers to the 
right of the Government to use this dirigible balloon without liability for infringe- 
ment of other inventors' patents. It does not contemplate the exclusive pur- 
chase of patent rights for duplicating the airship. 

17. The prices quoted in proposals must be understood to include the instruc- 
tion of two men in the handling and operation of this airship. No extra charge for 
this service will be allowed. 

JAMES ALLEN 
Brigadier General, Chief Signal Officer of the Army 
Sk;\ t al Office 

Washington, D. C, January 21, 1908 



APPENDIX NO. 3 



BIBLIOGRAPHY 

A List of Aeronautical "Works Compiled for the most Part from the 
Library of Congress, the Library of the Smithsonian Institution, and the 
Library of the Aeronautical Division of the Office of the Chief Signal 
Officer of the Army 

Adler, Cyrus. Partial Bibliography relating to Aerial Locomotion. National 

Geographic Magazine for January, 1907 
Aero Club of America, 1908. Constitution, By-Laws, List of Members, etc. 

Navigating the Air, 1907. Doubleday, Page & Co. 
Aero Club de Espana, Real. Estatutos 1907 
Aero Club de France. Status 1907 
Aero Club of the United Kingdom, The. 1906. 
Aeronautes Bibliophiles, Bulletin des. Catalogue de Livres d'Occasion sur 

la Navigation aerienne et des Sciences qui s'y attachent, 190S. Librairie 

des Sciences Aeronautiques, F. Louis Vivien. Paris 
Aeronautical Society of Great Britain, Annual Reports of. Volumes 

1 to 23 Hamilton and Company. Paternoster Row, London 
Aerostatic Spy, The, 1785; or: Excursions with an Air Balloon. E. Fawcett, 

London 
Aerial Navigation, 1S44-1S97. U. S. Patents. Volume 1, 1S44-1SS5. Vol- 
ume 2, 1886-1897 
Ahl, Dr. F. Von. Zur Mechanik Des Vogel fluges. 1S96. L. Friederichsen & 

Co., Hamburg 
Airships of Three Nations, with plates of "La Patrie" the ''Parseval" 

and British Military Airships. The Aeronautical Journal, October, 1907 
Alexander, John. The Conquest of the Air. 1902. A. Wessels Company 
Alix, Edmoxd. L'Appareil Locomoteur des Oiseaux. 1S74. G. Masson, Paris 
American Aeronautic Society of New York. The. 1879. The Balloon — 

History 
Amick, M. L. History of Donaldson's Balloon Ascensions. 1S75. Pub. Cincin- 
nati News Company 
Axdree, H. Letters from the Andree Party. 1897. Smithsonian Institution 

Report, 189 7 
Axdree, H. Au Pole Nord en Ballon Per Lamm. Paris 
Axdre, H. Les Dirigeables. 1902. C. Beranger. Paris 
Arago, Francis. Aeronautic Voyages Performed with a View to the \ .- 

vancement of Science. Smithsonian Institution Report. 1863 
Assman, Richard axd Bersox. Arthur. Wissenschaftliohe Luftfahrten 

(Three Volumes). 1S99-1900. Braunschweig, F. \ "ieweg und Sohn 



PRESENT STATUS OF MILITARY AERONAUTICS 1625 

Argyll,. Duke of. The Reign of Law. 1867. John W. Lovdl Company, New 

York 
Bacox, G. Dominion of the Air. 1905. David McKay, Philadelphia 

Balloons. Airships. Flying Machines, 1905. Dodd Mead 
Bacon, Gertrude. The Acoustical Experiments Carried Out in Balloons by 

the late Rev. J. M. Bacon. The Aeronautical Journal, January. 1906 
Bacox, Johx M. Scientific Ballooning. Smithsonian Institution Report, 1S9S 
Cloud Photography from a Balloon. The Aeronautical Journal, October, 
1900 
Badex-Powell, Major B. On the Action of a Bird's Wing, 1893. International 
Conference, Proceedings 
Recent Aeronautical Progress, and Deductions to be drawn therefrom regard- 
ing the Future of Aerial Navigation. Smithsonian Institution Report, 1902 
Recent Aeronautical Progress. The Aeronautical Journal, January 1903 
Progress with Air Ships. Smithsonian Institution Report, 1903 
The Development of the Aeroplane. The Aeronautical Journal, October 1904 
Ballooning as a Sport, 1907. W. Blackwood & Sons, London 
Experiments with Dipping Planes. The Aeronautical Journal, 1908 
Baldwix, Thomas. Airopaedia, 1786. J. Fletcher 

Balloon Photography, Captive, 1905. The Aeronautical Journal, 1905 
Balloxs. A Bound Volume of Pamphlets, 1783. Paris 

Balstox, R. M. The Stability of the Conic Shape in Ivites and Flying Ma- 
chines, 1907. The Aeronautical Journal, January, 1907 
Baxet-Rivet, M. L'Aeronautique, 1898. L. Henry May, Paris 
Bell, Alexaxder Graham. Description of Flights of Dr. Langley's Aerodrome, 
ISO 7. Aeronautical Annual No. 3 
The Tetrahedral Principle in Kite Structure. Judd and Detweiler, Wash- 
ington, D. C. Reprinted from National Geographical Magazine, June, 1903 
Graham Bell"s Tetrahedral Ivites. Smithsonian Institution Report, 1903 
Aerial Locomotion. Judd and Detweiler, Washington. Reprinted from 
National Geographic Magazine for January, 1907 
Berlix Coxgress of the Ixterxatioxal Aeroxautical Commissiox, The, 

The Aeronautical Journal, July, 1902 
Bezold, Wilhelm vox. Theoretische Betrachtungen uber die Ergenbisse der 
Wissenschaftlichen Luftfahrten, 1900. Friedrich Vieweg und Sohn Braun- 
schweig 
Blaxchet, Georges. Le Vade Mecum de l'Aeronaute, 1907. Georges Blanchet, 

Paris 
Blaxchard, Jeax Pierre. Journal of my 45th Ascension, 1793. C. Cist, Phila- 
delphia 
Blum, M. Soaring. Railroad and Engineering Journal for March, 1891 
Brissox, Mathurix Jacques. Dictionnaire Raisonne de Physique, 17S4. Le 

Boucher, Paris. (2 vols, and Atlas.) 
Borxeque. L' Aerostation Militaire en France et a L'Etranger, 1S99. Chape- 

lat et Cie 
Bretoxxiere, J. Sailing Flight,. International Conference, Proceedings, 1893 
Discussion of the Theory of the Aeroplane as contained in Prof. S. P. Lang- 
ley's Paper on the Internal Work of the Wind, 1893. International 
Conference, Proceedings, 1S93 



1626 PRESENT STATUS OF MILITARY AERONAUTICS 

Bretonniere, J. Reply to Criticisms on Sailing Flight. International Con- 
ference, Proceedings, 1893 
Brown, E. C. Brown's Directory of American Gas Companies. Press of 

"Progressive Age," 1907 
Carlotta. Sky-Larking in Cloudland, 1883. C. E. Myers 
Caulkins, Daxiel. Aerial Navigation, 1895. The Blade Printing Co., Toledo, 

Ohio 
Cavallo, Tiberius. The History and Practice of Aerostation, 1785. C. Dilly, 

London 
Cayley, Sir George. On Aerial Navigation. Aeronautical Annual Xo. 1, 

1895 
Chaxtjtf, Octave. Aerial Navigation. A lecture delivered to the students 

of Sibley College, Cornell University, May 2, 1S90. (Reprint.) Thj 

Railroad and Engineering Journal 
Progress in Aerial Navigation. The Engineering Magazine, New York, Octo- 
ber, 1891, vol. 2, Xo. 1 
Aerial Xavigation. Transportation, New York, October, 1893, vol. 1. Xo. 2. 

pp. 24-2.5 
Progress in Flying Machines. The Railroad and Engineering Journal, 

Xew York, continued from October, 1891, to March. 1893, and from May. 

1893, to December, 1893 
Progress in Flying Machines, 1893-1894. L'Aeronaute, Paris, 26-27, : 

1894, pp. 221-224 
Sailing Flight, parts 1 and 2. The Aeronautical Annual, 1896 and 1897, 

Boston. Nos. 2 and :•;, pp. 60-76, '.^-127 
American Gliding Experiments. Separate-Abdruck, Heft 1, 1898, der Illus- 

triten Aeronauti<chcn Mittheilungen, pp. 1-S 
Progress in Flying Machines. New York, 1899, pp. 1 6, 1 
Aerial Xavigation. The Independent, New York. 1900, pp. 1006-1<hi7. 

105S-1060 
Experiments in Flying. MeClu ine, New York, vol. 15, Xo. 2. 

June, 1900 
Aerial Navigation: Balloons and Flying Machines from an Engineering Stand- 
point. Cassier's Magazine, Xew York. June, 1901, vol. 20, Xo. 2, pp. 

111-123 
La Navigation Aerienne aux Etats-Unis. L'Aerophile, Aout, 1903, 11 

Annee, No! S, pp. 171-1S3 
L' Aviation en Amerique. Revue Generate des Sciences, pures et appliq 

Paris, 14 Annee, Xo. 22, November 30. 1003. pp. 1133-1H2 
Aeronautics. Encyclopaedia Britannica Supplement, pages 100-104, with 

three plates 
Aerial Xavigation. Scientific American Supplement, Xew York, vol. 57, 

1904, pp. 2359S-23600 
Aerial Xavigation. Smithsonian Institution Report, 1903-1904, pp. 173- 

1S1 
Aerial Xavigation. Popular Science Monthly, Xew York, vol. 04, 1904, pp. 

385-393 
Aerial Xavigation. Engineering World. Chicago, August 10, 1900, vol. 4, 

No. 9, p. 222 



PRESENT STATUS OF MILITARY AERONAUTICS 1627 

Chaxute, Octave. Opening Address. International Conference on Aerial 
Navigation, Proceedings, 1S93 
Recent Experiments in Gliding Flight. Aeronautical Annual, No. 3, 1897, 
Boston 

Chase, George Nathan. The Coming Railroad. 1894. Press of Nixon-Jones, 
Ptg. Co., St. Louis, Mo. 

Chatley, Herbert. The Problem of Flight, 1907. C. Griffin & Company, 
London. Lippincott, New York 

Chobham Common, Special Report and Photographs of the Kite Display 
ox. The Aeronautical Journal, July, 1907 

Coe, C. C. Observations in Balloons. International Conference, Proceedings, 
1S93 

Commission Permaxexte Internationale d'Aeroxautique, Li^te des Mem- 
bres de la. Paris, 1900 

Coxwell, Henry Tracey. My Life and Balloon Experiences, with Chapter 
on Military Ballooning, 1887-1889. TT. H. Allen & Co., London 

Coriosa axd Miscellaxy. Aerial Navigation, 1851. Longman Brown & Co., 
London 

Curtis, Thomas E. The Zeppelin Air Ship. Smithsonian Institution Re- 
port, 1900 

Darwin, Charles. Darwin's Observations. Aeronautical Annual, Xo 1, 
1895 

David, L. Solution du Probleme de la Navigation dans l'Air, 1864. F. Henry, 
Paris 

Dayidsox, Richard Oglesby. Disclosure of the Discover)'- and Invention of the 
Aerostat, 1840. St. Louis, Mo. 

Davis, J. TToodbridge. Some Experiments with Kites International Con- 
ference, Proceedings, 1893 

De Foxvielle, Wilfred. L'Aeronaute, Manuel Pratique de. Bernard Tignol, 
Paris 
Explorations of the L'pper Atmosphere. International Conference, Pro- 
ceedings, 1893 
Aeronautics in France. The Aeronautical Journal, July, 1901 

De Forge, L. Sazerac. La Conquete de L'Air, 1907. Berger, Levrault et Cie 

De Graffigxy, Hexry. Les BaUons, Dirigeables, 1902 Libraire J. B. Bailliere 
et Fils, Paris 

Deharme, E. Les Merveilles de la Locomotion, 188S. Libraire Hachette et 
Cie, Paris 

De La Vaulx, Henri, Comte. Seize Mille Kilometres en Ballon, 1903. Hach- 
ette et Cie, Paris 

Delmard, A. axd R. Bi.athwayt. European Military Ballooning, 1S99. Pall 
Mall Magazine, February, 1899 

De Louyrie, Ch. Theory of Soaring Flight. International Conference, Pro- 
ceedings, 1893 
The Ad\-antages of Beating Wings. International Conference, Proceedings, 
1893 

Dixes, W. H. Kites, Kite-Flying and Aeroplanes. The Aeronautical Jour- 
nal, January, 1905 



1628 PRESENT STATUS OF MILITARY AERONAUTICS 

Dow, J. H. The Elastic-Fluid Turbine a Possible Motor for Aeronautical Use. 
International Conference, Proceedings, 1893. 

Duchemin, Col. Les Lois de la Resistance des Fluides, 1842. Bachelier, Paris 

Dumont, A. Santos. My Air Ships, 1904. The Century Company, New York. 
Dans PAir, 1904. Charpentier et Fasquelle, Paris 

Dupoy de Lome, Stanislas Charles Henri Laurent. Note sur 1' Aerostat a 
Helice, etc., 1872. F. Didot freres, fils et Cie, Paris 

Duryea, C. E. Learning How to Fly. International Conference, Proceedings, 
1893 

Eddy, W. A . Experiments with Hexagon and Tailless Kites. International Con- 
ference, Proceedings, 1893 

Englehardt, Viktor. Electrolysis of Water, 1904. Chemical Publishing Co. 

Espitallier, G. La Technique du Ballon, 1907. Octave Doin 

Esschen, Napoleon F. Constant van. Moyen de Diriger un Ballon, 1847. 
E. Devroye, et Cie 

Farcot, Eugene. La Navigation Atmospherique, 1859. A. Bourdilliat et Cie, 
Paris 

Farman, M. Les Mervielles Aeriennes, 1896. Paris. 

Fassig, Oliver Lanard. Kite-Flying in the Tropics. Monthly Weather Re- 
view for December, 1903 

Faujas de Saint-Fond, Barthelemy. Description des experiences de la ma- 
chine Aerostatique de MM. de Montgolfier, 1784. Cuchet, Paris 

Federation Aeronautique Internationale. Status et Reglements, 1906 
Conference Statutaire. 1906 

Fergusson, Sterling Price. Materials used in Kite Experiments at Blue Hill 
Observatory, 1896. Aeronautical Annual, No. 2 
Anemometry. International Conference, Proceedings, 1S93 

Progress in Meteorological Kite-Flying. "Science," October 5, 1900 

Fitzgerald, M. F. The Distribution of Weight in Aeroplanes. The Aero- 
nautical Journal, July, 1907 
Theory of Flapping Wing Flight (?) Proc. Roy. Soc, vol. 14, page 420, 1S99 

Forster, Thomas Ignatius Maria. Annals of Some Remarkable Aerial and 
Alpine Voyages, 1832. Keating and Brown, London 

Foulois, Bexjamin D. The Practical and Strategical Value of Dirigible Bal- 
loons and Dynamical Flying Machines. Fort Leavenworth, Kansas, June 
1, 190S 

Frankenfield, Harry Crawford. Vertical Gradients of Temperature. Hu- 
midity and Wind Direction. Weather Bureau. 1S99 

Franklin, Benjamin. Aeronautical Correspondence. Aeronautical Journal 
No. 1, 1895 

Fullerton, Col. J. D. Notes on the Design of Flying Machines. International 
Conference, Proceedings, 1S93 
The Farman Flying Machine. The Aeronautical Journal, 190S 

Gerard, E. et A. De Rouville. Les Ballons dirigeables. 1907. Berger. Levrault 
et Cie 

Glaisher, James. An Account of Balloon Ascensions. 1863. Smithsonian 
Institution Report. 1863 
(Editor). Travels in the Air, 1871. R- Bentley. London 



PRESENT STATUS OF MILITARY AERONAUTICS 1629 

Goodrich, Samuel Griswold. The Balloon Travels of Robert Merry, etc., 1855. 

J. C. Derby & Co., New York 
Gouttes, Francois. Navigation Aerienne, 1893. Castelnaudary, Imp. H. Groe. 
Great Britain, Patent Office Library. Subject list of works on Aerial 
Navigation and Meteorology in the Library of the Patent Office, 1905. H. 
M. Stationery Office 
Grilleau, B. de. Les Aerostats Dirigeables, 1884. E. Dentil, Paris 
Gustin, Henry A. Aerial Navigation and its Solution, 1891. Cambridge, Mass. 
Guyton de Morveai:, Louis Bernard. Description de l'Aerostate l'Academie 

de Dijon, 1784. T. Barrois, Paris. 
Hald, Denmark. Station Franco-Scandinave de Sondages Aeriens, 1902-1903. 

1904. F. V. Backhausens Bogtrykkeri, Viborg, Denmark, 1904 
Hammer, William J. A Flight over Paris. Doubleday, Page Company 
Hansen, Christlln J. L. Krarup. Beitrage zu einer Theorie des Fluges der 

Vogel, 1869. C Steen und Sohn, Copenhagen 
Harding, Charles. Scientific Balloon Ascents, 1904. The Aeronautical Jour- 
nal, October, 1904 
Hargrave, Lawrence. "Aeronautics." (Reprint.) Journal and Proceedings 
of the Royal Society of New South Wales, vol., 32, pages 55 to 65 
Hargrave's Versuche, 111. aeron. Mitt., Strassburg, 7, 1903 (366-370) 
Flying Machines, Motors and Cellular Kites. International Conference, Pro- 
ceedings, 1893 
Flying Machine Memoranda. Journal and Proceedings of the Royal Society 

of New South Wales, Sydney, 1889, vol. 23, part 1, pages 70 to 74 
On a Compressed-air Flying-machine. Journal and Proceedings of the Royal 
Society of New South Wales, Sydney, 1890, vol. 24, part 1, pages 52 to 57 
Flying-Machine Work and the I I.H.P. Steam Motor weighing 3^ lbs. (Re- 
print.) Journal and Proceedings of the Royal Society of New South Wales, 
vol. 26, pages 170 to 175 
Flying-Machine Work and the I I. H. P. Steam Motor weighing 3J lbs. 
Journal of Proceedings of the Royal Society of New South Wales, Sydney, 
vol. 26, pages 170 to 175 
On the Cellular Kite. (Reprint.) Journal and Proceedings of the Royal 
Society of New South Wales, vol. 30, pages 1 to 4 
Harrington, Mark W. Systematic Exploration of the Upper Air, with Esti- 
mates of Cost. International Conference, Proceedings, 1893 
Hartwig, George Ludwig. The Aerial World. Longmans, Green & Co., 
London 

Hastings, C. W. On the Problem of Aerial Navigation. International Con- 
ference, Proceedings, 1893 

Hawkins, J. P. Automatic Stability. The Aeronautical Journal, April, 1905 

Hazex, II. A. Scientific Results Gained by Balloons. International Conference, 
Proceedings, 1893 
Ten Miles Above the Earth. International Conference, Proceedings, 1893 

Herring, A. M. Dynamic Flight. Aeronautical Annual, Boston, 1896, No. 2, 
pp. 89-101 
Recent Advances Toward a Solution of the Problem of the Century. 
Aeronautical Annual, Boston, 1897, No. 3, pp. 54-74 



1630 PRESENT STATUS OP MILITARY AERONAUTICS 

Herring, A. M. Die Regulirung von Flugmaschinen. Zeitschrift fur Luft- 

schiffahrt und Physik der Atmosphare, 1899, Heft 9, pp. 205-211 
Einige sehr Benzin- und Dampfmotoren, 1899. Zeitschrift fur Luftschiffahr 

und Physik der Atmosphare, 1899, Heft 1, pp. 1-4 
Hildebrandt, Alfred. Airship, Past and Present, 1908. D. Van Nostrand 

Company 
Die Luftschiffahrt, 1907. R. Oldenburg, Miinchen und Berlin 
Huffaker, E. C. Soaring Flight, 1893. International Conference, Proceed- 
ings, Smithsonian Institution Report, 1897 
The Way of an Eagle in the Air. Aeronautical Annual No. 3, 1897 
Hutchinson, Dr. F. W. H. Demonstration of a Bird-Like Flying-Machine, 

The Aeronautical Journal, October, 1905 
Hyatt, Thadeus. The Dragon Fly, 1882. C. Whittinham & Co., London 
Idees sur la Navigation Aerienne, Paris, 1784. Pamphlet of 23 pages 
International Balloon Ascents, The, July 22-27, 1907. Reports by W. H. 

Dines, J. E. Petavel, W. A. Harwood , W. E. Thrift. Journal Royal 

Meteorological Society, January, 1908 
International Conference on Aerial Navigation, Chicago, Preliminary 

Address, 1893 
International Conference on Aerial Navigation, Proceedings. Aug. 1. 

2, 3, 4, 1893, Chicago. The American Engineer and Railroad Journal. 

M. N. Forney, 47 Cedar St., New York 
Jahres-Bericht des Weiner Aero Klub, 1906 
Jahrbuch des Deutschen Luftschiffex Verbandes, 1907 
Janssen, Jules (i. e., Pierre Jules Cesar). The Progress of Aeronautic-. 1901. 

Smithsonian Institution Annual Report, 1900 
Julliot, H. Le Dirigeable Lebaudy, 1905. Paris 
Kennedy, Rankin. Mechanical Aerial Navigation. The Aeronautical Journal. 

January, 1908 
Kites, Man-Lifting. The Aeronautical Journal., January. 1905 
Kohlreif, Gottfried Albert. Abhandlung liber die Luft balle der Herreo von 

Montgolfier, 1784. Breitkopfsche Buchdruckerey 
Koutchino, Moscow, Russia. Bulletins oi the Institut Aerodynamique de 

Koutchino, near Moscow, Russia 
Kress, William. A Theory of Sailing Flight. International Conference. Pro- 
ceedings, 1893 
Aeroplanes and Flapping Flying Machines. International Conference. Pn 

ings, 1S93 
Note on the Elastic Screw. International Conference. Proceedings, 1893 
Kuhl, W. H. Aeronaut ische Bibliographie, 1670 -1895. 1895-1902. W. II. Kuhl. 

Jagerstr 73, Berlin 
Taschenbuch Zum praktischen Gebrauch fur Flugtechniker und Luftschiffer. 

W. H. Kuhl, Jagerstr 73, Berlin 
Lachambre, Henri and Machuron Alexis. Andree's Balloon Expedition in 

Search of the North Pole. F. A. Stokes Company. New York 
Lambert, Gustave. De la Locomotion Mecanique dans I' Air et dans l'Eau. 186 1 

Arthur Bert rand. Paris 
Lahens. Navigation Aerienne, 1905. Exposition a I' Automobile Club 



PEESENT STATUS OF MILITARY AERONAUTICS 1631 

Lahm, Frank P. The Conquest of the Air, 1908. Washington, D. C. 

Report on Dirigible Balloons and Light Motors in Europe, War Department, 

Jan. 11, 1908 
General Report on Aeronautics Abroad, War Department, Feb. 13, 1908 
Lamson, Charles H. Work on the Great Diamond. Aeronautical Annual, No. 

2, 1896 
Lancaster, F. W. Aerodynamics (Aerial Flight), 1908. D. Van Nostrand 

Company 
Langley, S. P. Locomotion Aerienne. Recherches experimentales aerodynami- 

ques et donnees d'experience. Note de M. S. P. Langley. Comptes Rendus 

Academie des Sciences, Paris, 1891, vol. 113, pp. 59-63 
Recherches experimentales aerodynamiques et donnes d'experience, 1891. 

(Separate.) Comptes Rendus Academie des Sciences, Paris, 1891, vol. 113, 

pp. 1-5 
L'Aeronaute, Paris, Aout, 1891, 23e annee, no. 8, pp. 176-180 
Experiments in Aerodynamics. Smithsonian Contributions to Knowledge, 

Washington, 1891, vol. 27, pp. 1-115, pis. 10 
The Possibility of Mechanical Flight. The Century, New York, September, 

1891, vol. 42, No. 5, pp. 783-785 
Experiences d' Aerodynamiques. Par M. S. P. Langley; Traduction libre et 

notes, par M. Lauriol. Revue de l'Aeronautique Theorique et Appliquee, 

4e annee, 3e et 4e livraisons, Paris, 1891, pp. 77-130, pis. 6 
Mechanical Flight. The Cosmopolitan, New York, May, 1892, pp. 55-58 
The Internal Work of the Wind, 1893. Smithsonian Contributions to Knowl- 
edge, Washington, pp. 1-23, pis. 5 
Le Travail Interieur du Vent. Revue de rAeronautique Theorique et Appli- 
quee, 6e annee, 3e livraison, Paris, 1893, pp. 37-68, pis. 5 
The Internal Work of the Wind. American Journal of Science, New Haven, 

1894, vol. 47, pp. 41-63, pis. 5 
The Internal Work of the Wind. From the American Journal of Science, New 

Haven, 1894, vol. 47, pp. 41-63, pis. 5 
The Internal Work of the Wind. Scientific American Supplement, New York, 

Feb. 17, 24, 1894; vol. 37, pp. 15122-24, 15137-39 
The Internal Work of the Wind. London, Edinburgh, and Dublin Philosophical 

Magazine and Journal of Science, fifth series, 1894, vol. 37, pp. 425-448 
Theorie du vol a voile, 1894. L'Aeronaute, Paris, Mars, 1894, 27e annee, No. 3, 

pp. 56-61 
Die innere Arbeit des Windes, 1894. Naturwissenschaftliche Rundschau 

Braunschweig, 31 Marz, no. 13, pp. 157-160 
Langley's Law, 1895. Aeronautical Annual, Boston, No. 1, pp. 127-128 
^ Locomotion Aerienne. Description du vol mecanique. Note de M. 
I Langley. Comptes Rendus Academie des Sciences, Paris, 1896, vol. 122, 
t pp. 1177-1178 
Description de vol mecanique. Extrait des Comptes Rendus des seances 

dc 1' Academie des Sciences, Paris, 1894, vol. 122, pp. 1-3 
A Successful Trial of the Aerodrome,. Science, New York. u.^. } vol. 3, No. 

73, May 22, 1896, pp. 753-754 
Experiments in Mechanical Flight. Nature, Loudon, May 28, 1896, vol. 

54, No. 1387, p. 80 



1632 PRESENT STATUS OF MILITARY AERONAUTICS 

Laxgley, S. P. L' Aeroplane. L'Aeronaute, Paris, 1896, 29e annee, no. 7, pp- 

147-166 
The New Flying Machine. Strand Magazine, London, June, 1897, pp. 707- 

719 
The "Flying Machine." McClure's Magazine, New York, vol. 9, No. 2, pp. 

647-660, 1897 
Story of Experiments in Mechanical Flight. Aeronautical Annual, Boston, 

No. 3, pp. 11-25, pis. 2, 1897 
A Rubber-Propelled Model. Aeronautical Annual, Boston and London, 1897, 

Xo. 3, pp. 153-154 
Methods of Launching Aerial Machines. Aeronautical Annual, Boston and 

London, 1897, no. 3, pp. 154-rl55 
Story of Experiments in Mechanical Flight. From Aeronautical Annual. Bos- 
ton, no. 3, pp. 11-25. Smithsonian Report for 1897, Washington, D. C. 
Xote on the Aerodrome of Mr. Langley. Prepared for the Conversazione 

of the American Institute of Electrical Engineers, Washington, 1901, pp. 1-3 
The Langley Aerodrome. Smithsonian Report for 1900, Washington, 1901, 

pp. 197-216, pis. 6 
The Greatest FlyiDg Creature. From the Annual Report of the Smithsonian 

Institution for 1901, Washington, 1902, pp. 649-659, pis. 7 
The Langley Aerodrome. Scientific American Supplement, New York, 1902, 

vol. 54, no. 1404, pp. 22494-22495 
The Langley Aerodrome. Conclusion. Scientific American Supplement. 

York, 1902, vol. 54, no. 1405, pp. 22510-22.312 
Experiments in Aerodynamics. Smithsonian Contributions to Knowledge, 
• Washington, 1902. Reprint of vol. 42, No. 5, pp. 7S3-7S5, Washington, 

1891 
The Greatest Flying Creature. Scientific American Supplement, January 31. 

1904, vol. 55, pp. 22644r-22645 
Experiments with the Langley Aerodrome. Annual Report of the Smithsonian 

Institution for 1904. Washington. 1905. pp. 113-125. pi. 1 
The Langley Aerodrome. From the Smithsonian Report for 1900, Washington, 

1901, pp. 197-216, pis. 6 
The Late Prof. S. P. Langley. The Aeronautical Journal, April. 1906 
Lecorxu, J. Les Cerfs- Volants, 1902. Librairie Nony £ Cie, Paris 
Leslie's Weekly, July 23, Editorial. The Aerodrome and the Warfare of 

the Future, 1S96 
Leslie, Sir Johx. Aerial Navigation, etc. Republished from Encylopaxlia 

Britannica, 1S3S. A. & C. Black, Edinburgh 
L'Expositiox Uxiverselle de 1SS9. Aerostats et Aerostation Militaire. 1S93. 

E. Bernard et Cie, Paris 
Liliexthal. Otto. Der Yogelflug. als Grundlage der Fliegekunst. Berlin. 

1889, pp. 1-8, 1-1S7. plates 1-S 
LTeber Theorie und Praxis des freien Fluges. Zeitschrift fur LuftschirTahrt Ber- 
lin, 10. 1891, Heft 7u. S. pp. 153-164 
Ueber meine diesjahrigen Flugversuche. Zeitschrift fur LuftschirTahrt. 

Berlin, 1891, Heft 12. pp. 286-291 
Ueber die Mechanik im Dienste der Flugteehnik. Zeitschrift fur Luft- 
schirTahrt und Physik der Atmosphare. Berlin. 1892, Heft 7u. S. pp. 180-186 



PRESENT STATUS OF MILITARY AERONAUTICS 1633 

Lilienthal, Otto. Ueber den Segelflug und Seine Nachahmung. Zeitschrift 
fur Luftschiffahrt und Physik der Atmosphare, 1892, Heft 11, pp. 277-281 

Die gewolbten Flugelflachen vor dem oesterichischen Ingenieur- und Arch- 
itekton Verein. Zeitschrift fur Luftschiffahrt und Physik der Atmosphare, 
1893, Heft |, pp. 88-90 

Die Flugmaschinen des Mr. Hargrave. Zeitschrift fur Luftschiffahrt und 
Physik der Atmosphare. Berlin 1893, Heft 5, pp. 114-118 

Ein begeisterter Flugtechniker in Chile. Zeitschrift fur Luftschiffahrt und 
Physik der Atmosphare. Berlin, 1893, Heft 5, p. 126 

Zur zweiten Auflage Buttenstedts a Flugprincip.' , Zeitschrift fur Luft- 
schiffahrt und Physik des Atmosphare, Berlin, 1893, Heft 6, pp. 143-145 

Ueber Schraubenflieger. Zeitschrift fur Luftschiffahrt und Physik der At- 
tmosphare, Berlin, 1893, Heft 9, pp. 228-230 

Die Tragfahigkeit gewolbter Flachen beim praktischen Segelfluge. Zeitschrift 
fur Luftschiffhart und Physik der Atmosphare, Berlin, 1893, Heft 11, 
pp. 259-272 

Die Tragfahigkeit gewolbter Flachen beim praktischen Segelfluge. Sep- 
aratabdruck aus Nr. 11 der Zeitschrift fur Luftschiffahrt und Physik der 
Atmosphare, November, 1893, pp. 259-272 

Allgemeine Gesichtspunkte bei Herstellung und Anwendung von Flugappar- 
aten. Zeitschrift fur Luftschiffahrt und Physik der Atmosphare, Ber- 
lin, 1894, Heft 6., pp. 143-155 

Maxim's Flugmaschine. Zeitschrift fur Luftschiffahrt und Physik der At- 
mosphare, Berlin, 1894, Heft 10, pp. 272-273 

Wellner's weitere luftschrauben-Versuche. Zeitschrift fur Luftschiffahrt 
Physik der Atmosphare, Berlin, 1894, Heft 12, pp. 334-336 

Resultate der praktischen Segelradversuche Prof. Wellner's. Zeitschrift fur 
Luftschiffahrt und Physik der Atmosphare, Berlin, 1895, Heft 1, pp. 25-26 

Die Profile der Segelflachen und ihre Wirkung. Zeitschrift fur Luft- 
schiffahrt und Physik der Atmosphare, Berlin, 1895, Heft f , pp. 42-57 

Ueber die Ermittelung der besten Flugelformen. Zeitschrift fur Luft- 
schiffahrt und Physik der Atmosphare, Berlin, 1895, Heft 10, pp. 237-245 

Lilienthal's Experiments in Flying. Nature, London, December 20, 1894, 
vol. 51, no. 1312, pp. 177-179 

Deux Lettres de M. Otto Lilienthal. L'Aeronaute, Paris, 27 Annee,No. 12, 
December, 1894, pp. 267-270 

Principes Generaux a Considerer dans la Construction et l'emploi des appareils 
de vol de M. Otto Lilientha. L'Aeronaute, Paris, 27 Annee, no. 12, De- 
cember, 1894, pp. 270-274 

Die Flugapparate. Berlin, Sonderabdruck aus Nr. 6 der Zeitschrift fur Luft- 
schiffahrt und Physik der Atmosphare, Berlin, 1894, pp. 3-15 

Les Experiences de M. Lilienthal par M. P. Lauriol. Revue de L'Aero-nau- 
tique, 8 Annee, Ire Livraison, 1895, pp. 1-10 

Practical Experiments for the Development of Human Flight. The Aero- 
nautical Annual, Boston, 1896, No. 2, pp. 7-22 

At Rhinow. The Aeronautical Annual, No. 3, Boston, 1897, pp. 92-94 

The Best Shapes for Wings. The Aeronautical Annual, Boston, 1897, No. 3, 
pp. 95-97 



163-1 PRESENT STATES OF MILITARY AERONAUTICS 

Lilienthal, Otto. Der Kunstflug. In: Taschenbuch f. Flugtechniker 2 

The Mechanism of Bird-Flight. 1889. A Partial Translation of " Der Vogelflug" 

by C. W. Shoemaker in Smithsonian Institution 
Der Vogelflug. 1889] R. Gaertners. Berlin 
The Problem of Flying and Practical Experiments in Soaring. Smithsonian 

Institution Report. 1893 
Our Teachers in Sailing Flight. Aeronautical Annual. No. 3. 1 v 
Lyle. E. P.. Jr. Santos-Dumont Circling the Eiffel Tower in an Air Ship. 

Smithsonian Institution Report. 1901 
Manfai, Eduard. Das Geloste Problem der Aeronautik. 1895. S 

Schurich 
Max-field. Charles Blackford. Aerial Navigation . 1877. Macmillan & 

London 
Marches, M. L. axd Yye. Ch. Dunod. Lessons in Aerial Navigation. 1903- 
Marey. E. J. Le Vol des Ois - Masson, Paris 

Animal Mechanism. 1873. International S 
Marion, F. Les Ballons. 1 SSI. Librairie Hachetl 
Marriott. AYilliam. Atmospheric Currents. T:. utical Journal. Jan- 

uary, P. 'i i2 
Marquis, Raoul. Les Ballons Dirig 3,1902 J. B. Bailliei 

Marshall. Alfred William. Flying Machines, 1 - - id Future, 

Spun and Chamberlain, New York 
Martin, Rudolf Emil. DasZeitall toriuftschiffahri 

pzig 
Die Eroberung der Luft, 1907. I - I rlin 

Marvin, Charles Frederick. Use of Kites in I the Uppei 

Air. U. S. Agriculture Dept., Yearbook, 1898 
Anemometry, 1900. I". S. Weather Bureau 
- .. Mow k. Details sur le Voyagi Aerien - - 

I H launay, Paris 
Aeronautica, 1838. F. C. ^ - odon 

Maxim. Hiram S. Improvements in and relating ( ratus 

British Patent Specification . 1^ 
Experiments in Aeronaut ics S ific American Supplement, December 

29, 1894 
A New Flying Machine. 1895 " gaane for Janu 

The Building of Modern Wonders; the Flying Machine. Harper's Young 

P< ople, January. 18 
Natural and Artificial Flight.. Aeronautical Annual. No. 2. 18 

w Propellers Working in Air. Aeronautical Annual, No. 3, 18 
Aerial Navigation by Means of Bodies heavier than Air. The Aeronau- 
tical Journal. January. 1 2 
Means. James. The Kite Considered as an Instrument of Value. Aeronautical 
Annual. No. 2, 18 
Edi1 Aeronautical Annual. No. 1. 1895; No. 2. 1896; No 3, 1897 

W. B. Clarke and Company. Boston. Mi — 
The Problem of Manflight. Aeronautical Magazine. No. 1, 18 
A Few Words about a Great Hope. Aeronautical Annual. No. 1, 18 



PRESENT STATUS OF MILITARY AERONAUTICS 1635 

Military Ballooning, Manual of, 1905. H. M. Stationery Office, London 
Millet, J. B. The Malay Kite. Aeronautical Annual, No. 2, 1896 

Some Experiments with Hargrave Kites. Aeronautical Annual, No. 2, 1896 
Scientific Kite-flying. Century Magazine for May, 1897 
Moedebeck, Herman W. (Collab, O. Chanute and others). Pocket-book of 

Aeronautics, 1907. Whittaker & Co., London 
Mora, Alfred. Projet d' Aerostat Mixte a densite variable et a volume constant 
indeformable, 1902. G. Camproger, Paris 
Aerolocomotion and Aerautomobiles, 1901. F. Bouchy & Cie 
Mouillard, L. P. The Empire of the Air. Smithsonian Institution Report 
for 1892 
A Programme for Safe Experimenting. International Conference, Proceed- 
ings, 1893 
L'Empire d l'Air, 1881. G. Masson, Paris 
Mullenhof, Karl. Otto Lilienthal, A. Memorial Address. Aeronautical 

Annual, No. 3, 1897 
Myers, Carl E. Manufacturing Hydrogen Gas Balloons. International Con- 
ference, Proceedings, 1893 
Natural Gas Balloon Ascensions. International Conference, Proceedings, 1893 
Maneuvering of Balloons. International Conference, Proceedings, 1893 
Balloon Meteorology. International Conference, Proceedings, 1893 
Xadar. Memoires du Geant. E. Dentu, Paris, 1865 
"Nature" Magazine, May 21. Sailing Flight, 1891 
Navigation Aerienne, La, 1886. Librairie Hachette et Cie, Paris 
Xemethy, Emil. Die Endgultige Losung des Flugproblems, 1903. J. J. Weber, 

Leipzig 
Newcomb, Simon. The Outlook for the Flying-Machine, 1906. Harper and 
Brothers, New York 
The Prospect of Aerial Navigation. North American Review for March, 190S 
Aerial Navigation. 19th Century Magazine, September, 1908 
Observatoire Coxstaxtin. Etude de l'atmosphere, 1906. C. Craiz, St. 

Petersburg 
Paris Expositiox Uxiyerselle, 1900. Aerial Navigation, Exhibitions, 1901- 

1902. Imprimere Nationale, Paris 
Pennington, John H. A System of Aerostation, 1842. Index Office, Wash- 
ington, D. C. 
Paris Enteb national Aeronautical Congress, The, 1901. The Aeronautical 

Journal, January, 1901 
Pettigrew, Jas. Bell. On the Various Modes of Flight in Relation to Aero- 
nautics. Smithsonian Institution Report, 1867 
On the Mechanical Appliances by which Flight is Attained in (lie Animal King- 
dom, 1868. Transactions of Linnean Society, London 
Aerial Locomotion. International Scientific Series, 1885 
Peyrey, Francois. Les Premiers Ilommes-Oiseaux Henri Guiton, Paris 
Pilcher, Percy S. Gliding Experiments. Aeronautical Annual, No. '3, 1897 
Pickerixg, William H. How a Bird Soars. Aeronautical Annual, No. 2, 1896 



1636 PRESENT STATUS OF MILITARY AERONAUTICS 

Pinchon, Edwin. High Explosives as a Means of Propulsion in Aerial Naviga- 
tion. "Transportation," New York, October, 1894 
Pole, W. "The Chicago Conference on Aerial Navigation," 1896. The Institu- 
tion of Civil Engineers , 1895-96, London 
Rayleigh, Lord. Lord Rayleigh on Flight. Smithsonian Institution Report 
1900. Manchester Philosophical Society, 1900 
Nature volume 27, page 534, 1883 
Reid, W. F. Balloon Varnishes and their Defects. The Aeronautical Journal 

October, 1905 
Rhees, William Joxes. Reminiscences of Ballooning in the Civil War, 1898. 

Meadville, Pa. 
Ritter vox Loessl, Friedrich. Die Luftwiderstandsgesetze der Fall durch 

die Luft und der Vogelflug, 1895. A. Holder, Vienna 
Rotch, Abbott Lawrence. The Relation of the Wind to Aeronautics, Aero- 
nautical Annual, No. 2, 1896 
The Exploration of the Free Air by means of Kites at Blue Hill Observatory, 

Massachusetts. Smithsonian Institution Report, 1897 
The Use of Kites to Obtain Meteorological Observations. Technology 

Quarterly, June, 1900 
Benjamin Franklin and the First Balloons, 1907. The Davis Press, Wor 

Mass. 
Sounding the Ocean of Air, 1900. E. and J. B. Young <k Co. New York 
The International Congresses of Aeronautics and Meteorology, 1900 
The Chief Scientific Uses of Kites. The Aeronautical Journal, October, 1901 
On the First Observations with Registration Balloons in America, 1905. 
American Academy or Arts and Science 
Sampaio, Dr. Carlos. The Peace Balloon of the late Senhor Augusto Severe, 

The Aeronautical Journal, October, 1902 
Samuelbon, A. Resistance of the Air, 1907. Spon. 

Flight Velocity, 1907. Spon. 
Schiavoxe Mario. II Principio della Dirigibilita Orizzontale degli Aerostatic 

ed il Binacrostato, 189S. Potenza, Garramone e Marehesiello 
Schools of Ballooning (Germany). Monthly Consular and Trade Reports, 

1907. Government Printing Office 
Scientific American Supplement. The Balloon in Modern Warfare. 
Seguix. Marc. Memoire but I' Aviation, 1SG6. A. Tramblay, Paris 
Sellers, M. B. Lift and Drift of Arched Surfaces. Scientific American Sup- 
plement, Nov. 14, 1908 
Setox, Valextixe E. axd Tomlinsox. F. L. Travels in Space. 1902. London 
Shaw, Dr. W. X. Contributions of Balloon Investigations to Meteorology. 
The Aeronautical Journal, January. 1903 
The Use of Kites in Meteorological Research. The Aeronautical Journal, 
January, 1907 
Silver. Thomas. The Scientific Explanation of the Polar Tides. An Aerial 

Exploration, 1SS7. Uptown Visitor Print. New York 
Smith. D. M. Boyer. The Balloon "Work of the late Mr. Coxwell. A Theory of 
Flight. The Aeronautical Journal, April, 1907 



PRESENT STATUS OF MILITARY AERONAUTICS 1637 

Smithsonian Institution. Aerodromics (Scrap-Books of Clippings) 

Aeronautica. (Scrap-books of Clippings) 
Smithsonian Meteorological Tables. Smithsonian Institution, 1907 

SOCIETE ROYALE DE GeOGRAPHIE D'ANVERS. CONGRES DE l' ATMOSPHERE, 1894. 

Part 8 contains : Contribution a la Bibliographic de la Locomotion Aerienne 

par Armand Wouwermans 
Soreau, R. Articles on Sailing Flight. Revue Scientifique, March 30, April 

5, 1895 
Starkweather, George B. The Secret of Wings, 1882. Beadle and Company, 

Washington 
Steinmann, Ferd. Die Luftschiff-fahrtskunde, 1848. B. Fr. Voigt, Weimar 
St. Louis, Universal Exposition, 1904. Rules and Regulations governing the 

Aeronautic Competition 
Stringfellow, F. J. A Few Remarks on What has been done with Screw-Pro- 
pelled Aero-Plane Machines from 1809 to 1892. Young and Son, Chard 
Taillepied, de la Garenne. Domitor (Le Dompteur de FAir), 1852. L. 

Mathias, Paris 
Tatin, Victor. Elements d'Aviation, 1908. H. Dunod and E. Pinat, Paris 
Taylor, George Crosland. Flying Devices. International Conference, Pro- 
ceedings, 1893 
Thurston, Robert H. Notes on the Materials of Aeronautic Engineering. 

International Conference, Proceedings, 1893. 
Tissandier, Albert. Histoire de mes Ascensions, 1887. Maurice Dreyfous, 

Paris 
Tissandier, Gaston. L'Ocean Aerien (Etudes Meteorologiques), 1885. G. 

Masson, Paris 
La Navigation Aerienne, 1886. Hachette et Cie, Paris 
La Photographie en Ballon, 1886. Gauthier Villars, Paris 
Bibliographic Aeronautique, 1887. H. Lannette et Cie, Paris 
Le Probleme de la Directione des Aerostats, 1883. Publications du Journal, 

Le Genie Civil, Paris 
Tournachon, Felix. The Right to Fly, 1866. Cassell, Petter and Galpin 

A Terre and en l'Air, 1865. E. Dentu, Paris 
Tsoucalas, Pelopidas D. and Jean G. Vlaharas. Etude Comparative des 

Aeroplanes et des Helicopteres, 1907 
Turnbull, W. R. Researches on the Forms and Stability of Aeroplanes. 

Physical Review, 1907 
Turnor, Christopher Hatton. Astra Castra, 1865. Chapman and Hall, 

London 

U. S. Weather Bureau. Bulletin of the Mount Weather Bureau, 1908. Wm. 

J. Humphreys, Wm. R. Blair 
Valentine, E. Seton. Travels in Space, 1902. Hurst and Blackett, London 
Van Salverda, J. G. W. Fijn.ie. Dc Luchtvaart. "De Ingenieur," 1893 

Aerial Navigation, 1894. 1). Appleton & Company 
Varney, George J. Kites: How to Make and Fly Them, 1897. G. II. Walker 

and Company, Boston 
Vaussin, Chardanne. Navigation Aerienne Serieuse, 1S73. Coutry & Puy- 

forcat 



1638 PRESENT STATUS OF MILITARY AERONAUTICS 

Yillars. Gauthier. La Science en Ballon. 1S69. Gauthier Yillars. Paris 

Yogt. H. C. Soaring. 1892. Louden Engineering, March 23. 1S92 
The Air Propeller. International Conference. Proceediogs. 1S93 

Yox JIelmholtz.. H. On a theorem relative to movements that are geometrically 
similar in fluid bodies, together with an appli cation to the problem of stf r- 
ing balloons. Smithsonian Institution Report, 1S91 

Von Lendenfeld, R. Relation of Wing Surface to Weight. Smithsonian 
Institution Report, 1904 

Walker. Frederick. Aerial Navigation. 1902. Crosby Lockwood & Son, 
London. Yan Xostrand 
Practical Kites and Aeroplanes. 1903. G. Pitman, London 

Walker. Thomas. A Treatise on the Art of Flying. 1816. S. Wood and S 
New York 

Walker, William George. The Lifting Power of Air Propellers. The Aero- 
nautical Journal, October 19 

Washington Academy of Sciences. Proceedings of Aerial Locomotion. 
Published by the Academy 

Weiss. Jose. The Starting Methods of Ae: The Aeronautical Jour- 

nal, January, 190S 

Weisse, Hermann. Der Dynamische Flug-Apparat. 1900. Emil Lehman. 
Berlin 

Wellington, A. M. The Mechanics of Flight and Aspirations. International 
Conference. Proceedings.. 1S93. 
Discussions of A. M Wellington's Paper on the Mechanics of Flight and Aspira- 
tions. International Conference, Proceeding 

Wellmax. Walter. The Polar Airship. 1906. Judd and Detweiler, Washing- 
ton. D. C 

Wexham. F. II. On Aerial Locomotion. Smithsonian Institution Report, 
1889 
Suggestions and Experiments for the Construction of Aerial Machines. Inter- 
national Conference, Pn 
Some Remarks on Aerial Flight. The Aeronautical Journal. October 1905 

Wexham. J. M. On Forms of Surfaces Impelled through the Air and their 
ects in Sustaining 2 Aeronautical Journal. July, 1900. 

Wood. De Volson. Flotation Versus Aviation. International Conference. 
Proceedings, 1893 

Winter, Wilhelm. Der Vogelflug. 1895. Theodor Ackermann. Muncheu 

Wise. J. History and Practi oautics. >' ^ Phila- 

delphia 

Wise. Johx. System of Aeronautics. 1850 

Through the Air. 1^73. To-day Publishing Company An enlarged edition of 
System of Aeronautics 

Woglom. Gilbert Tottex. Parakites. - G.P. Putn sS as N rYork 

Woodward. Calvix M. Air-Ship Propeller Problems. 1908. Transaction 
of the Acader..; S ace of St. Louis 

Wraenlow, Jerry. Newly Discovered Properties ycloid. l v v 

Kima Co... Seattle. Washington 



PRESENT STATUS OF MILITARY AERONAUTICS 1639 

Wright, Wilbur. Experiments and Observations in Soaring Flight. Journal 
of the Western Society of Engineers, August, 1903 

Some Aeronautical Experiments. Smithsonian Institution Report, 1902 
Wright, Wilbur and Orville. The Wright Aeroplane. Century Maga- 
zine for September, 1908 

Conference sur 1' Aerostation et le navire aerien dirigeables M. L.-A. Boisset. 
1893. Imprimerie Chaix, Paris 
Zahm, A. F. Resistance of the Air Determined at Speeds below One Thousand 
Feet a Second. Printed privately as a Doctor's Thesis 

Soaring. "Notre Dame Scholastic," Dec. 10, 1892 

Stability of Aeroplanes and Flying Machines. International Conference Pro- 
ceedings, 1893 

Atmospheric Gusts and their Relation to Flight. International Conference 
Proceedings, 1893 

Aerial Navigation. Journal of the Franklin Institute, November, 1894 

Resistance of the Air at Speeds below One Thousand Feet a Second. The Philo- 
sophical Magazine. May, 1901 

Theory of Balloon Leakage, Aeronautics, July, 1907 

Some Theorems in the Mechanics of High Speed Balloons. 1900. Catholic 
University of Amerca 

Determination of the Speed of an Aeroplane. Scientific American Supplement, 
July 18, 1908 

The Resistance of the Air. Philosophical Magazine, 1901 

Measurement of Air Velocity and Pressure. The Physical Review, Decem- 
ber, 1903 

Atmospheric Friction on Even Surfaces. Philosophical Magazine, 1904 

Atmospheric Friction with Special Reference to Aeronautics. Philosophical 
Society of Washington, 1904 

Law of Resistance of Rods and Wires, in Navigating the Air. 1907. Double- 
day, Page and Co 

Resume of Experiments in Aerodynamics. Monthly Weather Bureau, Septem- 
ber, 1908 
Zurcher et Margole. I^es Ancensions Celebres. 1879. Libraire Hachette et 

Cie, Paris 
Zeppelin's, Count Von, Dirigible Air Ship. Smithsonian Institution Report, 

1899 
Zeppelin Air Ship, The. Smithsonian Institution Report, 1900. (Reprinted 

from Strand Magazine for September, 1900) 
Zeppelin Airship, The Experiments with the. The Aeronautical Journal. 
April 1901 

LIST OF AERONAUTICAL PUBLICATIONS 

American Aeronaut, St. Louis 

Aeronautics, New York 

Fly, Philadelphia 

Aeronautical World, Glenville, Ohio (Ceased publication) 

Aeronautical Annual, Boston (Ceased publication) 

Tlic Aeronautical Journal, London 



1640 PRESENT STATUS OF MILITARY AERONAUTICS 

Ballooning and Aeronautics, London (Ceased publication) 

Flying, London 

The Balloon, London 

L'Aeronaute, Paris 

L'Aerophile, Paris 

Aerostat, Paris (Bulletin Aeronautique) 

Aerostat, Paris (Academie d'Aerostation) 

Revue de U Aerostation , Paris 

Le Ballon, Paris 

V Aerostation, Paris 

L' Aeronautique, Paris 

Bulletin Aeronautique, Paris 

L'Aeronauta, Milan 

Illustrierte Aeronautische MitteUungen, Berlin 

Weiner Luftschiffer-Zcitung, Vienna 

Illustrierte MittheiLungen des Obenheinische Verein fur Luftschiffahrt, Strain 

Boilettino delta Societa Aeronautica, Rome 

Vozdookhoplavatel, St. Petersburg 

AERONAUTICAL SOCIETIES OF THE WORLD 

INTERNATIONAL SCIENTIFIC xxlETIES 

The International Commission for Scientific Aeronautic-. Paris 
The Permanent International Aeronautica] Committee, Paris 

Federation Aeronautique Internationale. Paris 

xatioxal societies (Germany') 

Deutscher Luftschiffer-Yerband. Augsburg 
Berliner Verein fur Luftschiffahrt, Berlin 
Miinchener Verein fur Luftschiffahrt. Munich 
Oberrheinischer Verein fur Luftschiffahrt. Strassbourg 
Augsburger Verein fur Luftschiffahrt. Augsburg 
Niedcrrheinisehcr Verein fur Luftschiffahrt. Barmen 
Posener Verein fur Luftschiffahrt, Posen 
Ostdeutscher Verein fur Luftschiffahrt, Graudenz 
Frankischer Verein fur Luftschiffahrt, Wurzburg 
Mittelrheinischer Verein fur Luftschiffahrt, Coblenz 
Kolner Klub fur Luftschiffahrt. Kallenburg 
Physikalischer Verein im Frankfort. Frankfort 
Motorluftschiff-Studeingesellschaft, Berlin 

SOCIETIES OF OTHER NATIONS. 

Wiener Flugtechnischer Verein, Vienna 

Wiener Aero Club. Vienna 

Aero Club Suisse. Berne 

Aeronautical Society of Great Britain. London 

Aero Club of the United Kingdom, London 



PRESENT STATUS OF MILITARY AERONAUTICS 1641 

Aero Club of America, New York 

Aero Club of New England, Boston 

Aero Club of Philadelphia, Philadelphia 

The Philadelphia Aeronautical Recreation Society,Philadelphia 

Aero Club of Ohio, Canton, Ohio 

Aero Club of St. Louis, St. Louis 

Milwaukee Aero Club, Milwaukee 

Ben Franklin Aeronautical Society, Philadelphia 

North Adams Aero Club, North Adams, Mass. 

Pittsfield Aero Club, Pittsfield, Mass. 

The Aeronautical Society, New York 

Aero Club of Chicago, Chicago 

Aeronautique Club of Chicago, Chicago 

Aero Club of San Antonio, San Antonio, Texas 

Svenska Aeronautiska Sallskapet, Stockholm 

Societe Francais de Navigation Aerienne, Paris 

Aeronautique Club de France, Paris and Lyons 

Aero Club de France, Paris 

Academie Aeronautique de France, Paris 

Societe des Aeronautes du Siege, Paris 

Aero Club du Sud-Ouest, Bordeaux 

Aero Club du Rhone, Lyon 

Aero Club du Nord, Roubaix 

Club Aeronautique de FAube, Troye 

Automobile Club de Nice, Nice 

Aero Club de Belgique, Brussels 

Societa Aeronautica Italiana, Rome 

Aviation Club de France, Paris 

Russian Aeronautical Society, St. Petersburg 

El Real Aero-Club de Espana, Madrid 




Fig. 4 French Dirigible "La Ville de Paris" 




Fig. 6 German Dirigible "Zeppelin" with Floating Hangar 





Fig. 8 Signal Corps Dirigible No. 1. in Flight, Fort .Mykk. Va., 
August, L908 




Fig. 9 Signal Cori 



Dirigible N< 

AlUGUST, 



1. IX 

1908 



Flight, Fort Myer, Va., 




Fig. 12 Signal Corps Dirigible No. 1, Showing Details of Engine 



m 







i^*i.^V.V> 





Fig. 19 Wright Brothers' Aeroplane. Fort Myf.r. Va. 

1908 



> : ;i < i:\iiu i ; 12 




Fig. 20 Wright Brothers' Aeroplane, Fort Myer, Va., September 12, 
1908. Time of Flight, 1 Hr., 14 Mix.. 20 Sec. 




Fig. 21 Wright Brothers' Aeroplane, Fort Myer, Va., September 12 ; 
1908. Time of Flight, 1 Hr., 14 Mix., 20 sec. 




3 W 

3 55 




Fig. 23 Wright Brothers' Aeroplane, Fort Mter 
1908. Orville Wright and Passenger. Time, 



Va., September 
9 Min.. 6 Sec. 



L2. 




Fig. 24 Farm ax Aeroplane 




Fig. 25 "June Bug" Aeroplane, Hammondsport, N. Y. Aerial Experiment 

Association 



LI ; P "03 



THE PRESENT STATUS 



OF 



MILITARY AERONAUTICS 



GEORGE O. SQUIEK, Ph.D. 

Major Signal Corps. I". S. Army 



Reprint from The Journal 

The American Society of Mechanical Engineers 



